21618680 has 32 divisors (see below), whose sum is σ = 49777200. Its totient is φ = 8445696.

The previous prime is 21618677. The next prime is 21618683. The reversal of 21618680 is 8681612.

It is an interprime number because it is at equal distance from previous prime (21618677) and next prime (21618683).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21618683) 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, 4565 + ... + 8004.

Almost surely, 2^21618680 is an apocalyptic number.

21618680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21618680 is an abundant number, since it is smaller than the sum of its proper divisors (28158520).

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

21618680 is a wasteful number, since it uses less digits than its factorization.

21618680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12623 (or 12619 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 21618680 is about 4649.5892291685. The cubic root of 21618680 is about 278.5755891805.

The spelling of 21618680 in words is "twenty-one million, six hundred eighteen thousand, six hundred eighty".