21975939 has 12 divisors (see below), whose sum is σ = 32838000. Its totient is φ = 14145264.

The previous prime is 21975929. The next prime is 21975949. The reversal of 21975939 is 93957912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21975929) and next prime (21975949).

It is not a de Polignac number, because 21975939 - 2⁴ = 21975923 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21975894 and 21975903.

It is not an unprimeable number, because it can be changed into a prime (21975929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41839 + ... + 42360.

It is an arithmetic number, because the mean of its divisors is an integer number (2736500).

Almost surely, 2^21975939 is an apocalyptic number.

21975939 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21975939 is a deficient number, since it is larger than the sum of its proper divisors (10862061).

21975939 is a wasteful number, since it uses less digits than its factorization.

21975939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84234 (or 84231 counting only the distinct ones).

The product of its digits is 153090, while the sum is 45.

The square root of 21975939 is about 4687.8501469224. The cubic root of 21975939 is about 280.1017444869.

The spelling of 21975939 in words is "twenty-one million, nine hundred seventy-five thousand, nine hundred thirty-nine".