21320307 has 32 divisors (see below), whose sum is σ = 33211200. Its totient is φ = 13499136.

The previous prime is 21320297. The next prime is 21320311. The reversal of 21320307 is 70302312.

It is not a de Polignac number, because 21320307 - 2⁸ = 21320051 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21320307.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320317) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 56973 + ... + 57345.

It is an arithmetic number, because the mean of its divisors is an integer number (1037850).

Almost surely, 2^21320307 is an apocalyptic number.

21320307 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21320307 is a deficient number, since it is larger than the sum of its proper divisors (11890893).

21320307 is a wasteful number, since it uses less digits than its factorization.

21320307 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484 (or 478 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 18.

The square root of 21320307 is about 4617.3917962417. The cubic root of 21320307 is about 277.2880485275.

Adding to 21320307 its reverse (70302312), we get a palindrome (91622619).

The spelling of 21320307 in words is "twenty-one million, three hundred twenty thousand, three hundred seven".