21655313 has 4 divisors (see below), whose sum is σ = 21672960. Its totient is φ = 21637668.

The previous prime is 21655247. The next prime is 21655321. The reversal of 21655313 is 31355612.

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 21655313 - 2¹⁰ = 21654289 is a prime.

It is a super-2 number, since 2×21655313² = 937905162255938, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21655393) 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, 6833 + ... + 9486.

It is an arithmetic number, because the mean of its divisors is an integer number (5418240).

Almost surely, 2^21655313 is an apocalyptic number.

It is an amenable number.

21655313 is a deficient number, since it is larger than the sum of its proper divisors (17647).

21655313 is a wasteful number, since it uses less digits than its factorization.

21655313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17646.

The product of its digits is 2700, while the sum is 26.

The square root of 21655313 is about 4653.5269420086. The cubic root of 21655313 is about 278.7328497965.

The spelling of 21655313 in words is "twenty-one million, six hundred fifty-five thousand, three hundred thirteen".