21973940 has 24 divisors (see below), whose sum is σ = 46503072. Its totient is φ = 8721440.

The previous prime is 21973933. The next prime is 21973961. The reversal of 21973940 is 4937912.

It is a self number, because there is not a number n which added to its sum of digits gives 21973940.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1574 + ... + 6813.

It is an arithmetic number, because the mean of its divisors is an integer number (1937628).

Almost surely, 2^21973940 is an apocalyptic number.

21973940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21973940 is an abundant number, since it is smaller than the sum of its proper divisors (24529132).

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

21973940 is a wasteful number, since it uses less digits than its factorization.

21973940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8527 (or 8525 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 21973940 is about 4687.6369313333. The cubic root of 21973940 is about 280.0932512531.

The spelling of 21973940 in words is "twenty-one million, nine hundred seventy-three thousand, nine hundred forty".