991679280 has 80 divisors (see below), whose sum is σ = 3081659904. Its totient is φ = 263806720.

The previous prime is 991679279. The next prime is 991679281. The reversal of 991679280 is 82976199.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (991679279) and next prime (991679281).

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (991679281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 98647 + ... + 108233.

Almost surely, 2^991679280 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991679280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1540829952).

991679280 is an abundant number, since it is smaller than the sum of its proper divisors (2089980624).

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

991679280 is a wasteful number, since it uses less digits than its factorization.

991679280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10034 (or 10028 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 51.

The square root of 991679280 is about 31490.9396493658. The cubic root of 991679280 is about 997.2186981987.

The spelling of 991679280 in words is "nine hundred ninety-one million, six hundred seventy-nine thousand, two hundred eighty".