19961399172 has 144 divisors (see below), whose sum is σ = 55925795520. Its totient is φ = 5491699200.

The previous prime is 19961399147. The next prime is 19961399191. The reversal of 19961399172 is 27199316991.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1353454 + ... + 1368122.

It is an arithmetic number, because the mean of its divisors is an integer number (388373580).

Almost surely, 2^19961399172 is an apocalyptic number.

19961399172 is a gapful number since it is divisible by the number (12) 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 19961399172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27962897760).

19961399172 is an abundant number, since it is smaller than the sum of its proper divisors (35964396348).

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

19961399172 is a wasteful number, since it uses less digits than its factorization.

19961399172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14774 (or 14759 counting only the distinct ones).

The product of its digits is 1653372, while the sum is 57.

The spelling of 19961399172 in words is "nineteen billion, nine hundred sixty-one million, three hundred ninety-nine thousand, one hundred seventy-two".