21956636 has 12 divisors (see below), whose sum is σ = 41379912. Its totient is φ = 10133808.

The previous prime is 21956621. The next prime is 21956687. The reversal of 21956636 is 63665912.

It is a self number, because there is not a number n which added to its sum of digits gives 21956636.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 211070 + ... + 211173.

It is an arithmetic number, because the mean of its divisors is an integer number (3448326).

Almost surely, 2^21956636 is an apocalyptic number.

21956636 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21956636 is a deficient number, since it is larger than the sum of its proper divisors (19423276).

21956636 is a wasteful number, since it uses less digits than its factorization.

21956636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422260 (or 422258 counting only the distinct ones).

The product of its digits is 58320, while the sum is 38.

The square root of 21956636 is about 4685.7908617436. The cubic root of 21956636 is about 280.0197094969.

The spelling of 21956636 in words is "twenty-one million, nine hundred fifty-six thousand, six hundred thirty-six".