21939936 has 48 divisors (see below), whose sum is σ = 57834000. Its totient is φ = 7282688.

The previous prime is 21939919. The next prime is 21939937. The reversal of 21939936 is 63993912.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21939937) 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, 42850 + ... + 43358.

It is an arithmetic number, because the mean of its divisors is an integer number (1204875).

Almost surely, 2^21939936 is an apocalyptic number.

It is an amenable number.

21939936 is an abundant number, since it is smaller than the sum of its proper divisors (35894064).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21939936 is a wasteful number, since it uses less digits than its factorization.

21939936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 971 (or 963 counting only the distinct ones).

The product of its digits is 78732, while the sum is 42.

The square root of 21939936 is about 4684.0085397019. The cubic root of 21939936 is about 279.9486980840.

The spelling of 21939936 in words is "twenty-one million, nine hundred thirty-nine thousand, nine hundred thirty-six".