21704190 has 16 divisors (see below), whose sum is σ = 52090128. Its totient is φ = 5787776.

The previous prime is 21704171. The next prime is 21704191. The reversal of 21704190 is 9140712.

It is a super-2 number, since 2×21704190² = 942143727112200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21704190.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21704191) 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, 361707 + ... + 361766.

It is an arithmetic number, because the mean of its divisors is an integer number (3255633).

Almost surely, 2^21704190 is an apocalyptic number.

21704190 is an abundant number, since it is smaller than the sum of its proper divisors (30385938).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21704190 is a wasteful number, since it uses less digits than its factorization.

21704190 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723483.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21704190 is about 4658.7755902168. The cubic root of 21704190 is about 278.9423963501.

Subtracting from 21704190 its sum of digits (24), we obtain a triangular number (21704166 = T₆₅₈₈).

The spelling of 21704190 in words is "twenty-one million, seven hundred four thousand, one hundred ninety".