1961904640 has 40 divisors (see below), whose sum is σ = 4703979060. Its totient is φ = 784760832.

The previous prime is 1961904629. The next prime is 1961904643. The reversal of 1961904640 is 464091691.

It can be written as a sum of positive squares in 2 ways, for example, as 1940226304 + 21678336 = 44048^2 + 4656^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 1961904593 and 1961904602.

It is not an unprimeable number, because it can be changed into a prime (1961904643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 380625 + ... + 385744.

Almost surely, 2^1961904640 is an apocalyptic number.

1961904640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1961904640 is an abundant number, since it is smaller than the sum of its proper divisors (2742074420).

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

1961904640 is an frugal number, since it uses more digits than its factorization.

1961904640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 766392 (or 766376 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 1961904640 is about 44293.3927352602. The cubic root of 1961904640 is about 1251.8701903816.

The spelling of 1961904640 in words is "one billion, nine hundred sixty-one million, nine hundred four thousand, six hundred forty".