21355513 has 12 divisors (see below), whose sum is σ = 22506640. Its totient is φ = 20257776.

The previous prime is 21355511. The next prime is 21355561. The reversal of 21355513 is 31555312.

It is not a de Polignac number, because 21355513 - 2¹ = 21355511 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21355511) 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, 56158 + ... + 56536.

Almost surely, 2^21355513 is an apocalyptic number.

It is an amenable number.

21355513 is a deficient number, since it is larger than the sum of its proper divisors (1151127).

21355513 is an equidigital number, since it uses as much as digits as its factorization.

21355513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504 (or 475 counting only the distinct ones).

The product of its digits is 2250, while the sum is 25.

The square root of 21355513 is about 4621.2025491207. The cubic root of 21355513 is about 277.4405922120.

The spelling of 21355513 in words is "twenty-one million, three hundred fifty-five thousand, five hundred thirteen".