19978500064 has 48 divisors (see below), whose sum is σ = 40683202560. Its totient is φ = 9647556480.

The previous prime is 19978500053. The next prime is 19978500109. The reversal of 19978500064 is 46000587991.

It is a junction number, because it is equal to n+sod(n) for n = 19978499990 and 19978500017.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 478957 + ... + 518995.

It is an arithmetic number, because the mean of its divisors is an integer number (847566720).

Almost surely, 2^19978500064 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 19978500064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20341601280).

19978500064 is an abundant number, since it is smaller than the sum of its proper divisors (20704702496).

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

19978500064 is a wasteful number, since it uses less digits than its factorization.

19978500064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40583 (or 40575 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 49.

The spelling of 19978500064 in words is "nineteen billion, nine hundred seventy-eight million, five hundred thousand, sixty-four".