21668670 has 24 divisors (see below), whose sum is σ = 56338776. Its totient is φ = 5778288.

The previous prime is 21668629. The next prime is 21668681. The reversal of 21668670 is 7686612.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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, 120292 + ... + 120471.

It is an arithmetic number, because the mean of its divisors is an integer number (2347449).

Almost surely, 2^21668670 is an apocalyptic number.

21668670 is an abundant number, since it is smaller than the sum of its proper divisors (34670106).

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

21668670 is a wasteful number, since it uses less digits than its factorization.

21668670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240776 (or 240773 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 21668670 is about 4654.9618688019. The cubic root of 21668670 is about 278.7901455046.

It can be divided in two parts, 216 and 68670, that added together give a palindrome (68886).

The spelling of 21668670 in words is "twenty-one million, six hundred sixty-eight thousand, six hundred seventy".