20961580 has 24 divisors (see below), whose sum is σ = 45440640. Its totient is φ = 8113920.

The previous prime is 20961571. The next prime is 20961583. The reversal of 20961580 is 8516902.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is not an unprimeable number, because it can be changed into a prime (20961583) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16285 + ... + 17524.

It is an arithmetic number, because the mean of its divisors is an integer number (1893360).

Almost surely, 2^20961580 is an apocalyptic number.

20961580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20961580 is an abundant number, since it is smaller than the sum of its proper divisors (24479060).

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

20961580 is a wasteful number, since it uses less digits than its factorization.

20961580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33849 (or 33847 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 20961580 is about 4578.3818102033. The cubic root of 20961580 is about 275.7240643452.

The spelling of 20961580 in words is "twenty million, nine hundred sixty-one thousand, five hundred eighty".