21522513 has 4 divisors (see below), whose sum is σ = 28696688. Its totient is φ = 14348340.

The previous prime is 21522511. The next prime is 21522521. The reversal of 21522513 is 31522512.

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 not a de Polignac number, because 21522513 - 2¹ = 21522511 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21522513.

It is not an unprimeable number, because it can be changed into a prime (21522511) 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, 3587083 + ... + 3587088.

It is an arithmetic number, because the mean of its divisors is an integer number (7174172).

Almost surely, 2^21522513 is an apocalyptic number.

It is an amenable number.

21522513 is a deficient number, since it is larger than the sum of its proper divisors (7174175).

21522513 is an equidigital number, since it uses as much as digits as its factorization.

21522513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7174174.

The product of its digits is 600, while the sum is 21.

The square root of 21522513 is about 4639.2362517983. The cubic root of 21522513 is about 278.1619098934.

Subtracting 21522513 from its reverse (31522512), we obtain a palindrome (9999999).

The spelling of 21522513 in words is "twenty-one million, five hundred twenty-two thousand, five hundred thirteen".