21660552 has 48 divisors (see below), whose sum is σ = 59670000. Its totient is φ = 7096416.

The previous prime is 21660523. The next prime is 21660559. The reversal of 21660552 is 25506612.

21660552 is a `hidden beast` number, since 2 + 1 + 6 + 605 + 52 = 666.

It is not an unprimeable number, because it can be changed into a prime (21660559) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1699 + ... + 6797.

It is an arithmetic number, because the mean of its divisors is an integer number (1243125).

Almost surely, 2^21660552 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 21660552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29835000).

21660552 is an abundant number, since it is smaller than the sum of its proper divisors (38009448).

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

21660552 is a wasteful number, since it uses less digits than its factorization.

21660552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5170 (or 5163 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 21660552 is about 4654.0898143461. The cubic root of 21660552 is about 278.7553256304.

The spelling of 21660552 in words is "twenty-one million, six hundred sixty thousand, five hundred fifty-two".