991297920060 has 768 divisors, whose sum is σ = 3841543372800. Its totient is φ = 207096652800.

The previous prime is 991297920047. The next prime is 991297920061. The reversal of 991297920060 is 60029792199.

991297920060 is a `hidden beast` number, since 9 + 91 + 297 + 9 + 200 + 60 = 666.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 991297919979 and 991297920006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991297920061) by changing a digit.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 1204492809 + ... + 1204493631.

It is an arithmetic number, because the mean of its divisors is an integer number (5002009600).

Almost surely, 2^991297920060 is an apocalyptic number.

991297920060 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 991297920060, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1920771686400).

991297920060 is an abundant number, since it is smaller than the sum of its proper divisors (2850245452740).

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

991297920060 is a wasteful number, since it uses less digits than its factorization.

991297920060 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1439 (or 1431 counting only the distinct ones).

The product of its (nonzero) digits is 1102248, while the sum is 54.

The spelling of 991297920060 in words is "nine hundred ninety-one billion, two hundred ninety-seven million, nine hundred twenty thousand, sixty".