15521664 has 64 divisors (see below), whose sum is σ = 41811840. Its totient is φ = 5101056.

The previous prime is 15521659. The next prime is 15521677. The reversal of 15521664 is 46612551.

15521664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (64).

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, 31629 + ... + 32115.

It is an arithmetic number, because the mean of its divisors is an integer number (653310).

Almost surely, 2^15521664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15521664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20905920).

15521664 is an abundant number, since it is smaller than the sum of its proper divisors (26290176).

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

15521664 is an equidigital number, since it uses as much as digits as its factorization.

15521664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587 (or 575 counting only the distinct ones).

The product of its digits is 7200, while the sum is 30.

The square root of 15521664 is about 3939.7543070603. The cubic root of 15521664 is about 249.4476552264.

The spelling of 15521664 in words is "fifteen million, five hundred twenty-one thousand, six hundred sixty-four".