21836991 has 24 divisors (see below), whose sum is σ = 32771200. Its totient is φ = 12917520.

The previous prime is 21836981. The next prime is 21837019. The reversal of 21836991 is 19963812.

It is not a de Polignac number, because 21836991 - 2⁷ = 21836863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21836921) 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, 14910 + ... + 16308.

Almost surely, 2^21836991 is an apocalyptic number.

21836991 is a deficient number, since it is larger than the sum of its proper divisors (10934209).

21836991 is a wasteful number, since it uses less digits than its factorization.

21836991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1467 (or 1456 counting only the distinct ones).

The product of its digits is 23328, while the sum is 39.

The square root of 21836991 is about 4673.0066338493. The cubic root of 21836991 is about 279.5101597151.

The spelling of 21836991 in words is "twenty-one million, eight hundred thirty-six thousand, nine hundred ninety-one".