21588066 has 64 divisors (see below), whose sum is σ = 51580800. Its totient is φ = 6671808.

The previous prime is 21588037. The next prime is 21588067. The reversal of 21588066 is 66088512.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21588066.

It is not an unprimeable number, because it can be changed into a prime (21588067) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 54180 + ... + 54576.

It is an arithmetic number, because the mean of its divisors is an integer number (805950).

Almost surely, 2^21588066 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21588066, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25790400).

21588066 is an abundant number, since it is smaller than the sum of its proper divisors (29992734).

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

21588066 is a wasteful number, since it uses less digits than its factorization.

21588066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 480 (or 474 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 21588066 is about 4646.2959440828. The cubic root of 21588066 is about 278.4440310114. Note that the first 3 decimals are identical.

The spelling of 21588066 in words is "twenty-one million, five hundred eighty-eight thousand, sixty-six".