21890986 has 16 divisors (see below), whose sum is σ = 36900864. Its totient is φ = 9663984.

The previous prime is 21890959. The next prime is 21890987. The reversal of 21890986 is 68909812.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21890987) 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, 17706 + ... + 18901.

It is an arithmetic number, because the mean of its divisors is an integer number (2306304).

Almost surely, 2^21890986 is an apocalyptic number.

21890986 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21890986 is a deficient number, since it is larger than the sum of its proper divisors (15009878).

21890986 is a wasteful number, since it uses less digits than its factorization.

21890986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36645.

The product of its (nonzero) digits is 62208, while the sum is 43.

The square root of 21890986 is about 4678.7803966418. The cubic root of 21890986 is about 279.7403460227.

It can be divided in two parts, 218 and 90986, that added together give a square (91204 = 302²).

The spelling of 21890986 in words is "twenty-one million, eight hundred ninety thousand, nine hundred eighty-six".