1991557332 has 72 divisors (see below), whose sum is σ = 5075233800. Its totient is φ = 658471680.

The previous prime is 1991557319. The next prime is 1991557349. The reversal of 1991557332 is 2337551991.

1991557332 is a `hidden beast` number, since 1 + 9 + 91 + 557 + 3 + 3 + 2 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 902161296 + 1089396036 = 30036^2 + 33006^2 .

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 congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3680982 + ... + 3681522.

Almost surely, 2^1991557332 is an apocalyptic number.

1991557332 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1991557332 is an abundant number, since it is smaller than the sum of its proper divisors (3083676468).

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

1991557332 is a wasteful number, since it uses less digits than its factorization.

1991557332 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1193 (or 1188 counting only the distinct ones).

The product of its digits is 255150, while the sum is 45.

The square root of 1991557332 is about 44626.8678264563. The cubic root of 1991557332 is about 1258.1457002435.

The spelling of 1991557332 in words is "one billion, nine hundred ninety-one million, five hundred fifty-seven thousand, three hundred thirty-two".