21812986 has 16 divisors (see below), whose sum is σ = 35459424. Its totient is φ = 10003824.

The previous prime is 21812983. The next prime is 21813013. The reversal of 21812986 is 68921812.

It is not an unprimeable number, because it can be changed into a prime (21812983) 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, 1665 + ... + 6811.

It is an arithmetic number, because the mean of its divisors is an integer number (2216214).

Almost surely, 2^21812986 is an apocalyptic number.

21812986 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21812986 is a deficient number, since it is larger than the sum of its proper divisors (13646438).

21812986 is a wasteful number, since it uses less digits than its factorization.

21812986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5325.

The product of its digits is 13824, while the sum is 37.

The square root of 21812986 is about 4670.4374527447. The cubic root of 21812986 is about 279.4077020477.

The spelling of 21812986 in words is "twenty-one million, eight hundred twelve thousand, nine hundred eighty-six".