21645190 has 32 divisors (see below), whose sum is σ = 44700480. Its totient is φ = 7392384.

The previous prime is 21645181. The next prime is 21645203. The reversal of 21645190 is 9154612.

It is a super-2 number, since 2×21645190² = 937028500272200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25696 + ... + 26524.

It is an arithmetic number, because the mean of its divisors is an integer number (1396890).

Almost surely, 2^21645190 is an apocalyptic number.

21645190 is an abundant number, since it is smaller than the sum of its proper divisors (23055290).

21645190 is a wasteful number, since it uses less digits than its factorization.

21645190 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1216.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 21645190 is about 4652.4391452226. The cubic root of 21645190 is about 278.6894108428.

The spelling of 21645190 in words is "twenty-one million, six hundred forty-five thousand, one hundred ninety".