19991400 has 192 divisors, whose sum is σ = 73120320. Its totient is φ = 4454400.

The previous prime is 19991381. The next prime is 19991423. The reversal of 19991400 is 419991.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (33).

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, 85684 + ... + 85916.

It is an arithmetic number, because the mean of its divisors is an integer number (380835).

Almost surely, 2^19991400 is an apocalyptic number.

19991400 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 19991400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36560160).

19991400 is an abundant number, since it is smaller than the sum of its proper divisors (53128920).

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

19991400 is a wasteful number, since it uses less digits than its factorization.

19991400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 276 (or 267 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 19991400 is about 4471.1743423848. The cubic root of 19991400 is about 271.4028494290.

The spelling of 19991400 in words is "nineteen million, nine hundred ninety-one thousand, four hundred".