21525013 has 4 divisors (see below), whose sum is σ = 21983040. Its totient is φ = 21066988.

The previous prime is 21525001. The next prime is 21525017. The reversal of 21525013 is 31052512.

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.

It is a cyclic number.

It is not a de Polignac number, because 21525013 - 2⁵ = 21524981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21525017) 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, 228943 + ... + 229036.

It is an arithmetic number, because the mean of its divisors is an integer number (5495760).

Almost surely, 2^21525013 is an apocalyptic number.

It is an amenable number.

21525013 is a deficient number, since it is larger than the sum of its proper divisors (458027).

21525013 is an equidigital number, since it uses as much as digits as its factorization.

21525013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458026.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21525013 is about 4639.5056848764. The cubic root of 21525013 is about 278.1726796681.

Adding to 21525013 its reverse (31052512), we get a palindrome (52577525).

The spelling of 21525013 in words is "twenty-one million, five hundred twenty-five thousand, thirteen".