19978188625 has 16 divisors (see below), whose sum is σ = 25059372624. Its totient is φ = 15901401600.

The previous prime is 19978188619. The next prime is 19978188697. The reversal of 19978188625 is 52688187991.

It can be written as a sum of positive squares in 8 ways, for example, as 2306208529 + 17671980096 = 48023^2 + 132936^2 .

It is not a de Polignac number, because 19978188625 - 2³ = 19978188617 is a prime.

It is a Duffinian 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 15 ways as a sum of consecutive naturals, for example, 381024 + ... + 430273.

It is an arithmetic number, because the mean of its divisors is an integer number (1566210789).

Almost surely, 2^19978188625 is an apocalyptic number.

It is an amenable number.

19978188625 is a deficient number, since it is larger than the sum of its proper divisors (5081183999).

19978188625 is an equidigital number, since it uses as much as digits as its factorization.

19978188625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811509 (or 811499 counting only the distinct ones).

The product of its digits is 17418240, while the sum is 64.

The spelling of 19978188625 in words is "nineteen billion, nine hundred seventy-eight million, one hundred eighty-eight thousand, six hundred twenty-five".