20661568 has 28 divisors (see below), whose sum is σ = 41586912. Its totient is φ = 10183040.

The previous prime is 20661551. The next prime is 20661583. The reversal of 20661568 is 86516602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2271 + ... + 6817.

Almost surely, 2^20661568 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 20661568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20793456).

20661568 is an abundant number, since it is smaller than the sum of its proper divisors (20925344).

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

20661568 is an equidigital number, since it uses as much as digits as its factorization.

20661568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4630 (or 4620 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 20661568 is about 4545.4997525025. The cubic root of 20661568 is about 274.4023074092.

The spelling of 20661568 in words is "twenty million, six hundred sixty-one thousand, five hundred sixty-eight".