19805820400 has 120 divisors (see below), whose sum is σ = 50150361600. Its totient is φ = 7496006400.

The previous prime is 19805820341. The next prime is 19805820413. The reversal of 19805820400 is 402850891.

It is a self number, because there is not a number n which added to its sum of digits gives 19805820400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10935495 + ... + 10937305.

It is an arithmetic number, because the mean of its divisors is an integer number (417919680).

Almost surely, 2^19805820400 is an apocalyptic number.

19805820400 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 19805820400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25075180800).

19805820400 is an abundant number, since it is smaller than the sum of its proper divisors (30344541200).

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

19805820400 is a wasteful number, since it uses less digits than its factorization.

19805820400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3287 (or 3276 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The spelling of 19805820400 in words is "nineteen billion, eight hundred five million, eight hundred twenty thousand, four hundred".