21685190 has 8 divisors (see below), whose sum is σ = 39033360. Its totient is φ = 8674072.

The previous prime is 21685177. The next prime is 21685193. The reversal of 21685190 is 9158612.

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

It is a super-2 number, since 2×21685190² = 940494930672200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21685193) 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, 1084250 + ... + 1084269.

It is an arithmetic number, because the mean of its divisors is an integer number (4879170).

Almost surely, 2^21685190 is an apocalyptic number.

21685190 is a deficient number, since it is larger than the sum of its proper divisors (17348170).

21685190 is a wasteful number, since it uses less digits than its factorization.

21685190 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2168526.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 21685190 is about 4656.7359813500. The cubic root of 21685190 is about 278.8609765443.

The spelling of 21685190 in words is "twenty-one million, six hundred eighty-five thousand, one hundred ninety".