20961570 has 32 divisors (see below), whose sum is σ = 57495168. Its totient is φ = 4791168.

The previous prime is 20961559. The next prime is 20961571. The reversal of 20961570 is 7516902.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (20961571) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49699 + ... + 50118.

It is an arithmetic number, because the mean of its divisors is an integer number (1796724).

Almost surely, 2^20961570 is an apocalyptic number.

20961570 is an abundant number, since it is smaller than the sum of its proper divisors (36533598).

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

20961570 is a wasteful number, since it uses less digits than its factorization.

20961570 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99834.

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 20961570 is about 4578.3807181142. The cubic root of 20961570 is about 275.7240204993.

The spelling of 20961570 in words is "twenty million, nine hundred sixty-one thousand, five hundred seventy".