21331986 has 32 divisors (see below), whose sum is σ = 46122048. Its totient is φ = 6538560.

The previous prime is 21331963. The next prime is 21331993. The reversal of 21331986 is 68913312.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38020 + ... + 38576.

It is an arithmetic number, because the mean of its divisors is an integer number (1441314).

Almost surely, 2^21331986 is an apocalyptic number.

21331986 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21331986 is an abundant number, since it is smaller than the sum of its proper divisors (24790062).

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

21331986 is a wasteful number, since it uses less digits than its factorization.

21331986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1066.

The product of its digits is 7776, while the sum is 33.

The square root of 21331986 is about 4618.6562981023. The cubic root of 21331986 is about 277.3386709376.

The spelling of 21331986 in words is "twenty-one million, three hundred thirty-one thousand, nine hundred eighty-six".