21708190 has 16 divisors (see below), whose sum is σ = 44656992. Its totient is φ = 7442784.

The previous prime is 21708187. The next prime is 21708191. The reversal of 21708190 is 9180712.

It is a super-2 number, since 2×21708190² = 942491026152200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21708191) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 154989 + ... + 155128.

It is an arithmetic number, because the mean of its divisors is an integer number (2791062).

Almost surely, 2^21708190 is an apocalyptic number.

21708190 is an abundant number, since it is smaller than the sum of its proper divisors (22948802).

21708190 is a wasteful number, since it uses less digits than its factorization.

21708190 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310131.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 21708190 is about 4659.2048677859. The cubic root of 21708190 is about 278.9595313065.

The spelling of 21708190 in words is "twenty-one million, seven hundred eight thousand, one hundred ninety".