1961144640 has 504 divisors, whose sum is σ = 8458337160. Its totient is φ = 413392896.

The previous prime is 1961144639. The next prime is 1961144671. The reversal of 1961144640 is 464411691.

1961144640 is a `hidden beast` number, since 1 + 9 + 6 + 1 + 1 + 4 + 4 + 640 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 23736384 + 1937408256 = 4872^2 + 44016^2 .

It is a tau number, because it is divible by the number of its divisors (504).

It is a super-3 number, since 3×1961144640³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1961144595 and 1961144604.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1834026 + ... + 1835094.

It is an arithmetic number, because the mean of its divisors is an integer number (16782415).

Almost surely, 2^1961144640 is an apocalyptic number.

1961144640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1961144640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4229168580).

1961144640 is an abundant number, since it is smaller than the sum of its proper divisors (6497192520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1961144640 is a wasteful number, since it uses less digits than its factorization.

1961144640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1119 (or 1099 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 1961144640 is about 44284.8127465839. The cubic root of 1961144640 is about 1251.7085202363.

The spelling of 1961144640 in words is "one billion, nine hundred sixty-one million, one hundred forty-four thousand, six hundred forty".