21951938 has 6 divisors (see below), whose sum is σ = 32937849. Its totient is φ = 10972656.

The previous prime is 21951931. The next prime is 21951971. The reversal of 21951938 is 83915912.

It can be written as a sum of positive squares in 2 ways, for example, as 16785409 + 5166529 = 4097^2 + 2273^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3313.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21951931) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4970 + ... + 8282.

Almost surely, 2^21951938 is an apocalyptic number.

21951938 is a deficient number, since it is larger than the sum of its proper divisors (10985911).

21951938 is an frugal number, since it uses more digits than its factorization.

21951938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6628 (or 3315 counting only the distinct ones).

The product of its digits is 19440, while the sum is 38.

The square root of 21951938 is about 4685.2895321421. The cubic root of 21951938 is about 279.9997363943. Note that the first 3 decimals are identical.

The spelling of 21951938 in words is "twenty-one million, nine hundred fifty-one thousand, nine hundred thirty-eight".