21315051 has 12 divisors (see below), whose sum is σ = 31211128. Its totient is φ = 14014944.

The previous prime is 21315037. The next prime is 21315053. The reversal of 21315051 is 15051312.

It is not a de Polignac number, because 21315051 - 2¹⁸ = 21052907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21315053) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15565 + ... + 16878.

Almost surely, 2^21315051 is an apocalyptic number.

21315051 is a deficient number, since it is larger than the sum of its proper divisors (9896077).

21315051 is a wasteful number, since it uses less digits than its factorization.

21315051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32522 (or 32519 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21315051 is about 4616.8226086780. The cubic root of 21315051 is about 277.2652604604.

Adding to 21315051 its reverse (15051312), we get a palindrome (36366363).

The spelling of 21315051 in words is "twenty-one million, three hundred fifteen thousand, fifty-one".