19718890820 has 12 divisors (see below), whose sum is σ = 41409670764. Its totient is φ = 7887556320.

The previous prime is 19718890799. The next prime is 19718890861. The reversal of 19718890820 is 2809881791.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 2656783936 + 17062106884 = 51544^2 + 130622^2 .

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, 492972251 + ... + 492972290.

It is an arithmetic number, because the mean of its divisors is an integer number (3450805897).

Almost surely, 2^19718890820 is an apocalyptic number.

19718890820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19718890820 is an abundant number, since it is smaller than the sum of its proper divisors (21690779944).

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

19718890820 is a wasteful number, since it uses less digits than its factorization.

19718890820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 985944550 (or 985944548 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 53.

The spelling of 19718890820 in words is "nineteen billion, seven hundred eighteen million, eight hundred ninety thousand, eight hundred twenty".