991890280 has 16 divisors (see below), whose sum is σ = 2231753220. Its totient is φ = 396756096.

The previous prime is 991890271. The next prime is 991890301. The reversal of 991890280 is 82098199.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 926958916 + 64931364 = 30446^2 + 8058^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 991890280.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12398589 + ... + 12398668.

Almost surely, 2^991890280 is an apocalyptic number.

It is an amenable number.

991890280 is an abundant number, since it is smaller than the sum of its proper divisors (1239862940).

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

991890280 is a wasteful number, since it uses less digits than its factorization.

991890280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24797268 (or 24797264 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 46.

The square root of 991890280 is about 31494.2896411397. The cubic root of 991890280 is about 997.2894193912.

The spelling of 991890280 in words is "nine hundred ninety-one million, eight hundred ninety thousand, two hundred eighty".