21021365 has 16 divisors (see below), whose sum is σ = 26083200. Its totient is φ = 16251840.

The previous prime is 21021359. The next prime is 21021383. The reversal of 21021365 is 56312012.

It is not a de Polignac number, because 21021365 - 2⁴ = 21021349 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36530 + ... + 37100.

It is an arithmetic number, because the mean of its divisors is an integer number (1630200).

Almost surely, 2^21021365 is an apocalyptic number.

It is an amenable number.

21021365 is a deficient number, since it is larger than the sum of its proper divisors (5061835).

21021365 is a wasteful number, since it uses less digits than its factorization.

21021365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21021365 is about 4584.9062149623. The cubic root of 21021365 is about 275.9859484900.

Adding to 21021365 its reverse (56312012), we get a palindrome (77333377).

The spelling of 21021365 in words is "twenty-one million, twenty-one thousand, three hundred sixty-five".