15661240 has 32 divisors (see below), whose sum is σ = 40272480. Its totient is φ = 5369472.

The previous prime is 15661223. The next prime is 15661273. The reversal of 15661240 is 4216651.

It is a congruent number.

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, 27687 + ... + 28246.

It is an arithmetic number, because the mean of its divisors is an integer number (1258515).

Almost surely, 2^15661240 is an apocalyptic number.

15661240 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15661240 is an abundant number, since it is smaller than the sum of its proper divisors (24611240).

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

15661240 is a wasteful number, since it uses less digits than its factorization.

15661240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55951 (or 55947 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 15661240 is about 3957.4284579762. The cubic root of 15661240 is about 250.1931307636.

Adding to 15661240 its reverse (4216651), we get a palindrome (19877891).

The spelling of 15661240 in words is "fifteen million, six hundred sixty-one thousand, two hundred forty".