21633979 has 8 divisors (see below), whose sum is σ = 22967280. Its totient is φ = 20307456.

The previous prime is 21633973. The next prime is 21634021. The reversal of 21633979 is 97933612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21633979 - 2⁵ = 21633947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21633973) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5892 + ... + 8830.

It is an arithmetic number, because the mean of its divisors is an integer number (2870910).

It is a vampire number, since it can be written as 2939 ⋅ 7361 (with its own digits).

Almost surely, 2^21633979 is an apocalyptic number.

21633979 is a deficient number, since it is larger than the sum of its proper divisors (1333301).

21633979 is a wasteful number, since it uses less digits than its factorization.

21633979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3389.

The product of its digits is 61236, while the sum is 40.

The square root of 21633979 is about 4651.2341373016. The cubic root of 21633979 is about 278.6412873480.

It can be divided in two parts, 216339 and 79, that multiplied together give a triangular number (17090781 = T₅₈₄₆).

The spelling of 21633979 in words is "twenty-one million, six hundred thirty-three thousand, nine hundred seventy-nine".