21065886 has 16 divisors (see below), whose sum is σ = 46813200. Its totient is φ = 7021944.

The previous prime is 21065843. The next prime is 21065887. The reversal of 21065886 is 68856012.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21065886.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21065887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 195001 + ... + 195108.

It is an arithmetic number, because the mean of its divisors is an integer number (2925825).

Almost surely, 2^21065886 is an apocalyptic number.

21065886 is an abundant number, since it is smaller than the sum of its proper divisors (25747314).

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

21065886 is a wasteful number, since it uses less digits than its factorization.

21065886 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390120 (or 390114 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 21065886 is about 4589.7588171929. The cubic root of 21065886 is about 276.1806473325.

The spelling of 21065886 in words is "twenty-one million, sixty-five thousand, eight hundred eighty-six".