15921972 has 72 divisors (see below), whose sum is σ = 45357312. Its totient is φ = 4665600.

The previous prime is 15921967. The next prime is 15922001. The reversal of 15921972 is 27912951.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11628 + ... + 12924.

Almost surely, 2^15921972 is an apocalyptic number.

15921972 is a gapful number since it is divisible by the number (12) 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 15921972, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22678656).

15921972 is an abundant number, since it is smaller than the sum of its proper divisors (29435340).

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

15921972 is a wasteful number, since it uses less digits than its factorization.

15921972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1349 (or 1344 counting only the distinct ones).

The product of its digits is 11340, while the sum is 36.

The square root of 15921972 is about 3990.2345795705. The cubic root of 15921972 is about 251.5739209634.

The spelling of 15921972 in words is "fifteen million, nine hundred twenty-one thousand, nine hundred seventy-two".