1991267174400 has 1728 divisors, whose sum is σ = 8252359315200. Its totient is φ = 420804034560.

The previous prime is 1991267174399. The next prime is 1991267174401. The reversal of 1991267174400 is 44717621991.

It is an interprime number because it is at equal distance from previous prime (1991267174399) and next prime (1991267174401).

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991267174401) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 10107955102 + ... + 10107955298.

It is an arithmetic number, because the mean of its divisors is an integer number (4775670900).

Almost surely, 2^{1991267174400} is an apocalyptic number.

1991267174400 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 1991267174400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4126179657600).

1991267174400 is an abundant number, since it is smaller than the sum of its proper divisors (6261092140800).

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

1991267174400 is a wasteful number, since it uses less digits than its factorization.

1991267174400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342 (or 310 counting only the distinct ones).

The product of its (nonzero) digits is 762048, while the sum is 51.

The spelling of 1991267174400 in words is "one trillion, nine hundred ninety-one billion, two hundred sixty-seven million, one hundred seventy-four thousand, four hundred".