19721208400 has 60 divisors (see below), whose sum is σ = 47628451584. Its totient is φ = 7847152000.

The previous prime is 19721208391. The next prime is 19721208407. The reversal of 19721208400 is 480212791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19721208407) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52666 + ... + 205465.

Almost surely, 2^19721208400 is an apocalyptic number.

19721208400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19721208400 is an abundant number, since it is smaller than the sum of its proper divisors (27907243184).

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

19721208400 is a wasteful number, since it uses less digits than its factorization.

19721208400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258340 (or 258329 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 34.

The spelling of 19721208400 in words is "nineteen billion, seven hundred twenty-one million, two hundred eight thousand, four hundred".