21868686 has 24 divisors (see below), whose sum is σ = 54151344. Its totient is φ = 6248160.

The previous prime is 21868669. The next prime is 21868709. The reversal of 21868686 is 68686812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 86655 + ... + 86906.

It is an arithmetic number, because the mean of its divisors is an integer number (2256306).

Almost surely, 2^21868686 is an apocalyptic number.

21868686 is an abundant number, since it is smaller than the sum of its proper divisors (32282658).

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

21868686 is a wasteful number, since it uses less digits than its factorization.

21868686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173576 (or 173573 counting only the distinct ones).

The product of its digits is 221184, while the sum is 45.

The square root of 21868686 is about 4676.3966897602. The cubic root of 21868686 is about 279.6453247330.

The spelling of 21868686 in words is "twenty-one million, eight hundred sixty-eight thousand, six hundred eighty-six".