15904921 has 2 divisors, whose sum is σ = 15904922. Its totient is φ = 15904920.

The previous prime is 15904909. The next prime is 15904939. The reversal of 15904921 is 12940951.

15904921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9853321 + 6051600 = 3139^2 + 2460^2 .

It is an emirp because it is prime and its reverse (12940951) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15904921 - 2⁷ = 15904793 is a prime.

It is not a weakly prime, because it can be changed into another prime (15904901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7952460 + 7952461.

It is an arithmetic number, because the mean of its divisors is an integer number (7952461).

Almost surely, 2^15904921 is an apocalyptic number.

It is an amenable number.

15904921 is a deficient number, since it is larger than the sum of its proper divisors (1).

15904921 is an equidigital number, since it uses as much as digits as its factorization.

15904921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 15904921 is about 3988.0974160619. The cubic root of 15904921 is about 251.4840845392.

The spelling of 15904921 in words is "fifteen million, nine hundred four thousand, nine hundred twenty-one".