21415680 has 324 divisors, whose sum is σ = 87528168. Its totient is φ = 4792320.

The previous prime is 21415661. The next prime is 21415721. The reversal of 21415680 is 8651412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1647354 + ... + 1647366.

Almost surely, 2^21415680 is an apocalyptic number.

21415680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21415680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43764084).

21415680 is an abundant number, since it is smaller than the sum of its proper divisors (66112488).

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

21415680 is a wasteful number, since it uses less digits than its factorization.

21415680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21415680 is about 4627.7078559477. The cubic root of 21415680 is about 277.7009015113.

The spelling of 21415680 in words is "twenty-one million, four hundred fifteen thousand, six hundred eighty".