21951940 has 24 divisors (see below), whose sum is σ = 46310040. Its totient is φ = 8740608.

The previous prime is 21951931. The next prime is 21951971. The reversal of 21951940 is 4915912.

It can be written as a sum of positive squares in 4 ways, for example, as 10982596 + 10969344 = 3314^2 + 3312^2 .

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, 2184 + ... + 6976.

It is an arithmetic number, because the mean of its divisors is an integer number (1929585).

Almost surely, 2^21951940 is an apocalyptic number.

21951940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21951940 is an abundant number, since it is smaller than the sum of its proper divisors (24358100).

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

21951940 is a wasteful number, since it uses less digits than its factorization.

21951940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5031 (or 5029 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 21951940 is about 4685.2897455760. The cubic root of 21951940 is about 279.9997448977. Note that the first 3 decimals are identical.

The spelling of 21951940 in words is "twenty-one million, nine hundred fifty-one thousand, nine hundred forty".