21612959 has 4 divisors (see below), whose sum is σ = 21658560. Its totient is φ = 21567360.

The previous prime is 21612953. The next prime is 21612977. The reversal of 21612959 is 95921612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21612959 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 (21612953) 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, 22082 + ... + 23039.

It is an arithmetic number, because the mean of its divisors is an integer number (5414640).

Almost surely, 2^21612959 is an apocalyptic number.

21612959 is a deficient number, since it is larger than the sum of its proper divisors (45601).

21612959 is an equidigital number, since it uses as much as digits as its factorization.

21612959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45600.

The product of its digits is 9720, while the sum is 35.

The square root of 21612959 is about 4648.9739728245. The cubic root of 21612959 is about 278.5510136506.

The spelling of 21612959 in words is "twenty-one million, six hundred twelve thousand, nine hundred fifty-nine".