12561937920 has 480 divisors, whose sum is σ = 51920114400. Its totient is φ = 2870525952.

The previous prime is 12561937909. The next prime is 12561937939. The reversal of 12561937920 is 2973916521.

It is a happy number.

12561937920 is a `hidden beast` number, since 1 + 2 + 5 + 619 + 3 + 7 + 9 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3385026 + ... + 3388734.

It is an arithmetic number, because the mean of its divisors is an integer number (108166905).

Almost surely, 2^12561937920 is an apocalyptic number.

12561937920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 12561937920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25960057200).

12561937920 is an abundant number, since it is smaller than the sum of its proper divisors (39358176480).

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

12561937920 is an equidigital number, since it uses as much as digits as its factorization.

12561937920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3755 (or 3726 counting only the distinct ones).

The product of its (nonzero) digits is 204120, while the sum is 45.

The spelling of 12561937920 in words is "twelve billion, five hundred sixty-one million, nine hundred thirty-seven thousand, nine hundred twenty".