21718710 has 96 divisors (see below), whose sum is σ = 64078560. Its totient is φ = 5059584.

The previous prime is 21718703. The next prime is 21718721. The reversal of 21718710 is 1781712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 21742 + ... + 22718.

It is an arithmetic number, because the mean of its divisors is an integer number (667485).

Almost surely, 2^21718710 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21718710, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32039280).

21718710 is an abundant number, since it is smaller than the sum of its proper divisors (42359850).

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

21718710 is a wasteful number, since it uses less digits than its factorization.

21718710 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1022 (or 1019 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 27.

The square root of 21718710 is about 4660.3336790406. Note that the first 3 decimals coincide. The cubic root of 21718710 is about 279.0045861966.

The spelling of 21718710 in words is "twenty-one million, seven hundred eighteen thousand, seven hundred ten".