15939921 has 16 divisors (see below), whose sum is σ = 22169088. Its totient is φ = 10176000.

The previous prime is 15939919. The next prime is 15939923. The reversal of 15939921 is 12993951.

It is an interprime number because it is at equal distance from previous prime (15939919) and next prime (15939923).

It is not a de Polignac number, because 15939921 - 2¹ = 15939919 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 15939921.

It is not an unprimeable number, because it can be changed into a prime (15939923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8545 + ... + 10241.

It is an arithmetic number, because the mean of its divisors is an integer number (1385568).

Almost surely, 2^15939921 is an apocalyptic number.

It is an amenable number.

15939921 is a deficient number, since it is larger than the sum of its proper divisors (6229167).

15939921 is a wasteful number, since it uses less digits than its factorization.

15939921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1832.

The product of its digits is 21870, while the sum is 39.

The square root of 15939921 is about 3992.4830619553. The cubic root of 15939921 is about 251.6684194041.

The spelling of 15939921 in words is "fifteen million, nine hundred thirty-nine thousand, nine hundred twenty-one".