21664190 has 8 divisors (see below), whose sum is σ = 38995560. Its totient is φ = 8665672.

The previous prime is 21664187. The next prime is 21664193. The reversal of 21664190 is 9146612.

It is an interprime number because it is at equal distance from previous prime (21664187) and next prime (21664193).

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

It is a super-2 number, since 2×21664190² = 938674256712200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664193) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1083200 + ... + 1083219.

It is an arithmetic number, because the mean of its divisors is an integer number (4874445).

Almost surely, 2^21664190 is an apocalyptic number.

21664190 is a deficient number, since it is larger than the sum of its proper divisors (17331370).

21664190 is a wasteful number, since it uses less digits than its factorization.

21664190 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2166426.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21664190 is about 4654.4806369777. The cubic root of 21664190 is about 278.7709308822.

The spelling of 21664190 in words is "twenty-one million, six hundred sixty-four thousand, one hundred ninety".