21929970 has 16 divisors (see below), whose sum is σ = 52632000. Its totient is φ = 5847984.

The previous prime is 21929959. The next prime is 21929977. The reversal of 21929970 is 7992912.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21929977) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 365470 + ... + 365529.

It is an arithmetic number, because the mean of its divisors is an integer number (3289500).

Almost surely, 2^21929970 is an apocalyptic number.

21929970 is an abundant number, since it is smaller than the sum of its proper divisors (30702030).

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

21929970 is a wasteful number, since it uses less digits than its factorization.

21929970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 731009.

The product of its (nonzero) digits is 20412, while the sum is 39.

The square root of 21929970 is about 4682.9445864755. The cubic root of 21929970 is about 279.9063036839.

The spelling of 21929970 in words is "twenty-one million, nine hundred twenty-nine thousand, nine hundred seventy".