21258513 has 6 divisors (see below), whose sum is σ = 30706754. Its totient is φ = 14172336.

The previous prime is 21258487. The next prime is 21258527. The reversal of 21258513 is 31585212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13373649 + 7884864 = 3657^2 + 2808^2 .

It is not a de Polignac number, because 21258513 - 2⁵ = 21258481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21258563) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1181020 + ... + 1181037.

Almost surely, 2^21258513 is an apocalyptic number.

It is an amenable number.

21258513 is a deficient number, since it is larger than the sum of its proper divisors (9448241).

21258513 is a wasteful number, since it uses less digits than its factorization.

21258513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2362063 (or 2362060 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21258513 is about 4610.6955006810. The cubic root of 21258513 is about 277.0198954374.

The spelling of 21258513 in words is "twenty-one million, two hundred fifty-eight thousand, five hundred thirteen".