21171986 has 8 divisors (see below), whose sum is σ = 34645104. Its totient is φ = 9623620.

The previous prime is 21171961. The next prime is 21171989. The reversal of 21171986 is 68917112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21171989) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 481160 + ... + 481203.

It is an arithmetic number, because the mean of its divisors is an integer number (4330638).

Almost surely, 2^21171986 is an apocalyptic number.

21171986 is a deficient number, since it is larger than the sum of its proper divisors (13473118).

21171986 is a wasteful number, since it uses less digits than its factorization.

21171986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 962376.

The product of its digits is 6048, while the sum is 35.

The square root of 21171986 is about 4601.3026416440. The cubic root of 21171986 is about 276.6435396226.

The spelling of 21171986 in words is "twenty-one million, one hundred seventy-one thousand, nine hundred eighty-six".