21887866 has 72 divisors (see below), whose sum is σ = 45905184. Its totient is φ = 7600320.

The previous prime is 21887851. The next prime is 21887893. The reversal of 21887866 is 66878812.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 754740 + ... + 754768.

It is an arithmetic number, because the mean of its divisors is an integer number (637572).

Almost surely, 2^21887866 is an apocalyptic number.

21887866 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21887866 is an abundant number, since it is smaller than the sum of its proper divisors (24017318).

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

21887866 is a wasteful number, since it uses less digits than its factorization.

21887866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104 (or 62 counting only the distinct ones).

The product of its digits is 258048, while the sum is 46.

The square root of 21887866 is about 4678.4469645386. The cubic root of 21887866 is about 279.7270554481.

The spelling of 21887866 in words is "twenty-one million, eight hundred eighty-seven thousand, eight hundred sixty-six".