991309572 has 144 divisors (see below), whose sum is σ = 2893363200. Its totient is φ = 283020480.

The previous prime is 991309541. The next prime is 991309577. The reversal of 991309572 is 275903199.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (991309577) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2700933 + ... + 2701299.

It is an arithmetic number, because the mean of its divisors is an integer number (20092800).

Almost surely, 2^991309572 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 991309572, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1446681600).

991309572 is an abundant number, since it is smaller than the sum of its proper divisors (1902053628).

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

991309572 is a wasteful number, since it uses less digits than its factorization.

991309572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 766 (or 761 counting only the distinct ones).

The product of its (nonzero) digits is 153090, while the sum is 45.

The square root of 991309572 is about 31485.0690327971. The cubic root of 991309572 is about 997.0947584118.

The spelling of 991309572 in words is "nine hundred ninety-one million, three hundred nine thousand, five hundred seventy-two".