21897170 has 16 divisors (see below), whose sum is σ = 40062168. Its totient is φ = 8615040.

The previous prime is 21897151. The next prime is 21897179. The reversal of 21897170 is 7179812.

It can be written as a sum of positive squares in 4 ways, for example, as 13388281 + 8508889 = 3659^2 + 2917^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21897170.

It is not an unprimeable number, because it can be changed into a prime (21897179) 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, 17339 + ... + 18558.

Almost surely, 2^21897170 is an apocalyptic number.

21897170 is a deficient number, since it is larger than the sum of its proper divisors (18164998).

21897170 is a wasteful number, since it uses less digits than its factorization.

21897170 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35965.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21897170 is about 4679.4412059561. The cubic root of 21897170 is about 279.7666848916.

The spelling of 21897170 in words is "twenty-one million, eight hundred ninety-seven thousand, one hundred seventy".