21880566 has 12 divisors (see below), whose sum is σ = 47407932. Its totient is φ = 7293516.

The previous prime is 21880559. The next prime is 21880583. The reversal of 21880566 is 66508812.

It is a happy number.

21880566 is a `hidden beast` number, since 2 + 18 + 80 + 566 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21880566.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 607776 + ... + 607811.

It is an arithmetic number, because the mean of its divisors is an integer number (3950661).

Almost surely, 2^21880566 is an apocalyptic number.

21880566 is an abundant number, since it is smaller than the sum of its proper divisors (25527366).

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

21880566 is a wasteful number, since it uses less digits than its factorization.

21880566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1215595 (or 1215592 counting only the distinct ones).

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

The square root of 21880566 is about 4677.6667260505. Note that the first 3 decimals coincide. The cubic root of 21880566 is about 279.6959539760.

The spelling of 21880566 in words is "twenty-one million, eight hundred eighty thousand, five hundred sixty-six".