21169986 has 8 divisors (see below), whose sum is σ = 42339984. Its totient is φ = 7056660.

The previous prime is 21169979. The next prime is 21169987. The reversal of 21169986 is 68996112.

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

21169986 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21169987) 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, 1764160 + ... + 1764171.

It is an arithmetic number, because the mean of its divisors is an integer number (5292498).

Almost surely, 2^21169986 is an apocalyptic number.

21169986 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21169986 is a wasteful number, since it uses less digits than its factorization.

21169986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3528336.

The product of its digits is 46656, while the sum is 42.

The square root of 21169986 is about 4601.0853067510. The cubic root of 21169986 is about 276.6348283551.

It can be divided in two parts, 21169 and 986, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21169986 in words is "twenty-one million, one hundred sixty-nine thousand, nine hundred eighty-six".