21761790 has 16 divisors (see below), whose sum is σ = 52228368. Its totient is φ = 5803136.

The previous prime is 21761777. The next prime is 21761791. The reversal of 21761790 is 9716712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21761791) 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, 362667 + ... + 362726.

It is an arithmetic number, because the mean of its divisors is an integer number (3264273).

Almost surely, 2^21761790 is an apocalyptic number.

21761790 is an abundant number, since it is smaller than the sum of its proper divisors (30466578).

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

21761790 is a wasteful number, since it uses less digits than its factorization.

21761790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 725403.

The product of its (nonzero) digits is 5292, while the sum is 33.

The square root of 21761790 is about 4664.9533759728. The cubic root of 21761790 is about 279.1889369130.

The spelling of 21761790 in words is "twenty-one million, seven hundred sixty-one thousand, seven hundred ninety".