15799921 has 4 divisors (see below), whose sum is σ = 16000000. Its totient is φ = 15599844.

The previous prime is 15799909. The next prime is 15799933. The reversal of 15799921 is 12999751.

15799921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12999751 = 107 ⋅121493.

It is an interprime number because it is at equal distance from previous prime (15799909) and next prime (15799933).

It is a cyclic number.

It is not a de Polignac number, because 15799921 - 2¹³ = 15791729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15799981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99921 + ... + 100078.

It is an arithmetic number, because the mean of its divisors is an integer number (4000000).

Almost surely, 2^15799921 is an apocalyptic number.

It is an amenable number.

15799921 is a deficient number, since it is larger than the sum of its proper divisors (200079).

15799921 is an equidigital number, since it uses as much as digits as its factorization.

15799921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200078.

The product of its digits is 51030, while the sum is 43.

The square root of 15799921 is about 3974.9114455545. The cubic root of 15799921 is about 250.9294521922.

The spelling of 15799921 in words is "fifteen million, seven hundred ninety-nine thousand, nine hundred twenty-one".