1961538840 has 48 divisors (see below), whose sum is σ = 6375002400. Its totient is φ = 523076928.

The previous prime is 1961538827. The next prime is 1961538841. The reversal of 1961538840 is 488351691.

1961538840 is a `hidden beast` number, since 19 + 61 + 538 + 8 + 40 = 666.

It is a super-3 number, since 3×1961538840³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1961538841) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2724000 + ... + 2724719.

It is an arithmetic number, because the mean of its divisors is an integer number (132812550).

Almost surely, 2^1961538840 is an apocalyptic number.

1961538840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1961538840 is an abundant number, since it is smaller than the sum of its proper divisors (4413463560).

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

1961538840 is a wasteful number, since it uses less digits than its factorization.

1961538840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5448736 (or 5448729 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 45.

The square root of 1961538840 is about 44289.2632587177. The cubic root of 1961538840 is about 1251.7923812006.

The spelling of 1961538840 in words is "one billion, nine hundred sixty-one million, five hundred thirty-eight thousand, eight hundred forty".