21156733 has 4 divisors (see below), whose sum is σ = 22784188. Its totient is φ = 19529280.

The previous prime is 21156719. The next prime is 21156743. The reversal of 21156733 is 33765112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3541924 + 17614809 = 1882^2 + 4197^2 .

It is a cyclic number.

It is not a de Polignac number, because 21156733 - 2⁵ = 21156701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156703) 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, 813708 + ... + 813733.

It is an arithmetic number, because the mean of its divisors is an integer number (5696047).

Almost surely, 2^21156733 is an apocalyptic number.

It is an amenable number.

21156733 is a deficient number, since it is larger than the sum of its proper divisors (1627455).

21156733 is a wasteful number, since it uses less digits than its factorization.

21156733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1627454.

The product of its digits is 3780, while the sum is 28.

The square root of 21156733 is about 4599.6448775965. The cubic root of 21156733 is about 276.5770892726.

It can be divided in two parts, 211567 and 33, that added together give a square (211600 = 460²).

The spelling of 21156733 in words is "twenty-one million, one hundred fifty-six thousand, seven hundred thirty-three".