991529280 has 336 divisors, whose sum is σ = 3937040640. Its totient is φ = 224354304.

The previous prime is 991529243. The next prime is 991529299. The reversal of 991529280 is 82925199.

It is a tau number, because it is divible by the number of its divisors (336).

It is a hoax number, since the sum of its digits (45) 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 (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2761741 + ... + 2762099.

Almost surely, 2^991529280 is an apocalyptic number.

991529280 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 991529280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1968520320).

991529280 is an abundant number, since it is smaller than the sum of its proper divisors (2945511360).

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

991529280 is a wasteful number, since it uses less digits than its factorization.

991529280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526 (or 513 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The square root of 991529280 is about 31488.5579218865. The cubic root of 991529280 is about 997.1684163686.

The spelling of 991529280 in words is "nine hundred ninety-one million, five hundred twenty-nine thousand, two hundred eighty".