991512023040 has 2496 divisors, whose sum is σ = 4643471347200. Its totient is φ = 196199055360.

The previous prime is 991512023003. The next prime is 991512023053. The reversal of 991512023040 is 40320215199.

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

It is a junction number, because it is equal to n+sod(n) for n = 991512022986 and 991512023004.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 13582356444 + ... + 13582356516.

Almost surely, 2^991512023040 is an apocalyptic number.

991512023040 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 991512023040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2321735673600).

991512023040 is an abundant number, since it is smaller than the sum of its proper divisors (3651959324160).

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

991512023040 is a wasteful number, since it uses less digits than its factorization.

991512023040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The spelling of 991512023040 in words is "nine hundred ninety-one billion, five hundred twelve million, twenty-three thousand, forty".