21660912 has 320 divisors, whose sum is σ = 83328000. Its totient is φ = 5225472.

The previous prime is 21660901. The next prime is 21660923. The reversal of 21660912 is 21906612.

It is an interprime number because it is at equal distance from previous prime (21660901) and next prime (21660923).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 746914 + ... + 746942.

It is an arithmetic number, because the mean of its divisors is an integer number (260400).

Almost surely, 2^21660912 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21660912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41664000).

21660912 is an abundant number, since it is smaller than the sum of its proper divisors (61667088).

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

21660912 is a wasteful number, since it uses less digits than its factorization.

21660912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85 (or 73 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21660912 is about 4654.1284898464. The cubic root of 21660912 is about 278.7568699333.

The spelling of 21660912 in words is "twenty-one million, six hundred sixty thousand, nine hundred twelve".