21656718 has 12 divisors (see below), whose sum is σ = 46922928. Its totient is φ = 7218900.

The previous prime is 21656711. The next prime is 21656741. The reversal of 21656718 is 81765612.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21656711) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 601558 + ... + 601593.

It is an arithmetic number, because the mean of its divisors is an integer number (3910244).

Almost surely, 2^21656718 is an apocalyptic number.

21656718 is an abundant number, since it is smaller than the sum of its proper divisors (25266210).

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

21656718 is a wasteful number, since it uses less digits than its factorization.

21656718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1203159 (or 1203156 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21656718 is about 4653.6779003279. The cubic root of 21656718 is about 278.7388777427.

The spelling of 21656718 in words is "twenty-one million, six hundred fifty-six thousand, seven hundred eighteen".