19891040400 has 1800 divisors, whose sum is σ = 97352313696. Its totient is φ = 3832012800.

The previous prime is 19891040363. The next prime is 19891040437. The reversal of 19891040400 is 404019891.

It is an interprime number because it is at equal distance from previous prime (19891040363) and next prime (19891040437).

It is a tau number, because it is divible by the number of its divisors (1800).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 359 ways as a sum of consecutive naturals, for example, 296881167 + ... + 296881233.

Almost surely, 2^19891040400 is an apocalyptic number.

19891040400 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 19891040400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48676156848).

19891040400 is an abundant number, since it is smaller than the sum of its proper divisors (77461273296).

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

19891040400 is a wasteful number, since it uses less digits than its factorization.

19891040400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139 (or 112 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The spelling of 19891040400 in words is "nineteen billion, eight hundred ninety-one million, forty thousand, four hundred".