15397921 has 16 divisors (see below), whose sum is σ = 19289088. Its totient is φ = 11941200.

The previous prime is 15397909. The next prime is 15397939. The reversal of 15397921 is 12979351.

15397921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 15397921 - 2¹⁹ = 14873633 is a prime.

It is a super-2 number, since 2×15397921² = 474191942244482, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (15397951) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23626 + ... + 24268.

It is an arithmetic number, because the mean of its divisors is an integer number (1205568).

Almost surely, 2^15397921 is an apocalyptic number.

15397921 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

15397921 is a deficient number, since it is larger than the sum of its proper divisors (3891167).

15397921 is a wasteful number, since it uses less digits than its factorization.

15397921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 972.

The product of its digits is 17010, while the sum is 37.

The square root of 15397921 is about 3924.0184760014. The cubic root of 15397921 is about 248.7829972304.

The spelling of 15397921 in words is "fifteen million, three hundred ninety-seven thousand, nine hundred twenty-one".