21929931 has 12 divisors (see below), whose sum is σ = 31783752. Its totient is φ = 14570496.

The previous prime is 21929911. The next prime is 21929959. The reversal of 21929931 is 13992912.

It is a happy number.

It is not a de Polignac number, because 21929931 - 2²³ = 13541323 is a prime.

It is a super-2 number, since 2×21929931² = 961843747329522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21929911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1206 + ... + 6731.

It is an arithmetic number, because the mean of its divisors is an integer number (2648646).

Almost surely, 2^21929931 is an apocalyptic number.

21929931 is a deficient number, since it is larger than the sum of its proper divisors (9853821).

21929931 is a wasteful number, since it uses less digits than its factorization.

21929931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8250 (or 8247 counting only the distinct ones).

The product of its digits is 8748, while the sum is 36.

The square root of 21929931 is about 4682.9404224269. The cubic root of 21929931 is about 279.9061377565.

The spelling of 21929931 in words is "twenty-one million, nine hundred twenty-nine thousand, nine hundred thirty-one".