21333865 has 24 divisors (see below), whose sum is σ = 31354560. Its totient is φ = 13855968.

The previous prime is 21333863. The next prime is 21333877. The reversal of 21333865 is 56833312.

It is not a de Polignac number, because 21333865 - 2¹ = 21333863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21333863) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2364 + ... + 6946.

It is an arithmetic number, because the mean of its divisors is an integer number (1306440).

Almost surely, 2^21333865 is an apocalyptic number.

It is an amenable number.

21333865 is a deficient number, since it is larger than the sum of its proper divisors (10020695).

21333865 is a wasteful number, since it uses less digits than its factorization.

21333865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4621 (or 4614 counting only the distinct ones).

The product of its digits is 12960, while the sum is 31.

The square root of 21333865 is about 4618.8597077634. The cubic root of 21333865 is about 277.3468137028.

The spelling of 21333865 in words is "twenty-one million, three hundred thirty-three thousand, eight hundred sixty-five".