21704590 has 16 divisors (see below), whose sum is σ = 39247488. Its totient is φ = 8642016.

The previous prime is 21704569. The next prime is 21704603. The reversal of 21704590 is 9540712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2637 + ... + 7096.

It is an arithmetic number, because the mean of its divisors is an integer number (2452968).

Almost surely, 2^21704590 is an apocalyptic number.

21704590 is a deficient number, since it is larger than the sum of its proper divisors (17542898).

21704590 is a wasteful number, since it uses less digits than its factorization.

21704590 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9963.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21704590 is about 4658.8185197537. The cubic root of 21704590 is about 278.9441099405.

The spelling of 21704590 in words is "twenty-one million, seven hundred four thousand, five hundred ninety".