91256121815040 has 4160 divisors, whose sum is σ = 418930726368000. Its totient is φ = 18990284931072.

The previous prime is 91256121815039. The next prime is 91256121815057. The reversal of 91256121815040 is 4051812165219.

91256121815040 is a `hidden beast` number, since 9 + 1 + 2 + 5 + 61 + 2 + 1 + 81 + 504 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (4160).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 1250083860444 + ... + 1250083860516.

Almost surely, 2^{91256121815040} is an apocalyptic number.

91256121815040 is a gapful number since it is divisible by the number (90) 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 91256121815040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (209465363184000).

91256121815040 is an abundant number, since it is smaller than the sum of its proper divisors (327674604552960).

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

91256121815040 is an frugal number, since it uses more digits than its factorization.

91256121815040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174 (or 103 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 45.

The spelling of 91256121815040 in words is "ninety-one trillion, two hundred fifty-six billion, one hundred twenty-one million, eight hundred fifteen thousand, forty".