21052307 has 4 divisors (see below), whose sum is σ = 22290696. Its totient is φ = 19813920.

The previous prime is 21052301. The next prime is 21052331. The reversal of 21052307 is 70325012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21052307 - 2⁶ = 21052243 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21052301) 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, 619169 + ... + 619202.

It is an arithmetic number, because the mean of its divisors is an integer number (5572674).

Almost surely, 2^21052307 is an apocalyptic number.

21052307 is a deficient number, since it is larger than the sum of its proper divisors (1238389).

21052307 is a wasteful number, since it uses less digits than its factorization.

21052307 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1238388.

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 21052307 is about 4588.2793071041. The cubic root of 21052307 is about 276.1212928688.

Adding to 21052307 its reverse (70325012), we get a palindrome (91377319).

The spelling of 21052307 in words is "twenty-one million, fifty-two thousand, three hundred seven".