19991897280 has 448 divisors, whose sum is σ = 74741836800. Its totient is φ = 5016453120.

The previous prime is 19991897279. The next prime is 19991897297. The reversal of 19991897280 is 8279819991.

19991897280 is a `hidden beast` number, since 199 + 91 + 89 + 7 + 280 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 31682565 + ... + 31683195.

Almost surely, 2^19991897280 is an apocalyptic number.

19991897280 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 19991897280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37370918400).

19991897280 is an abundant number, since it is smaller than the sum of its proper divisors (54749939520).

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

19991897280 is a wasteful number, since it uses less digits than its factorization.

19991897280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 869 (or 853 counting only the distinct ones).

The product of its (nonzero) digits is 5878656, while the sum is 63.

The spelling of 19991897280 in words is "nineteen billion, nine hundred ninety-one million, eight hundred ninety-seven thousand, two hundred eighty".