15961640 has 32 divisors (see below), whose sum is σ = 38027880. Its totient is φ = 6008832.

The previous prime is 15961637. The next prime is 15961651. The reversal of 15961640 is 4616951.

15961640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 15952036 + 9604 = 3994^2 + 98^2 .

It is a junction number, because it is equal to n+sod(n) for n = 15961597 and 15961606.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11057 + ... + 12416.

Almost surely, 2^15961640 is an apocalyptic number.

15961640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15961640 is an abundant number, since it is smaller than the sum of its proper divisors (22066240).

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

15961640 is a wasteful number, since it uses less digits than its factorization.

15961640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23501 (or 23497 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 15961640 is about 3995.2021225465. The cubic root of 15961640 is about 251.7826714490.

The spelling of 15961640 in words is "fifteen million, nine hundred sixty-one thousand, six hundred forty".