19997865888 has 768 divisors, whose sum is σ = 74782310400. Its totient is φ = 4606156800.

The previous prime is 19997865847. The next prime is 19997865911. The reversal of 19997865888 is 88856879991.

It is a Harshad number since it is a multiple of its sum of digits (78).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 145969756 + ... + 145969892.

It is an arithmetic number, because the mean of its divisors is an integer number (97372800).

Almost surely, 2^19997865888 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19997865888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37391155200).

19997865888 is an abundant number, since it is smaller than the sum of its proper divisors (54784444512).

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

19997865888 is a wasteful number, since it uses less digits than its factorization.

19997865888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226 (or 204 counting only the distinct ones).

The product of its digits is 627056640, while the sum is 78.

The spelling of 19997865888 in words is "nineteen billion, nine hundred ninety-seven million, eight hundred sixty-five thousand, eight hundred eighty-eight".