21691710 has 48 divisors (see below), whose sum is σ = 58350240. Its totient is φ = 5584320.

The previous prime is 21691693. The next prime is 21691721. The reversal of 21691710 is 1719612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1546 + ... + 6765.

It is an arithmetic number, because the mean of its divisors is an integer number (1215630).

Almost surely, 2^21691710 is an apocalyptic number.

21691710 is an abundant number, since it is smaller than the sum of its proper divisors (36658530).

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

21691710 is a wasteful number, since it uses less digits than its factorization.

21691710 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8353 (or 8350 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 27.

The square root of 21691710 is about 4657.4359898983. The cubic root of 21691710 is about 278.8889217514. Note that the first 3 decimals are identical.

The spelling of 21691710 in words is "twenty-one million, six hundred ninety-one thousand, seven hundred ten".