131991220 has 12 divisors (see below), whose sum is σ = 277181604. Its totient is φ = 52796480.

The previous prime is 131991217. The next prime is 131991221. The reversal of 131991220 is 22199131.

It can be written as a sum of positive squares in 2 ways, for example, as 85451536 + 46539684 = 9244^2 + 6822^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131991221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3299761 + ... + 3299800.

It is an arithmetic number, because the mean of its divisors is an integer number (23098467).

Almost surely, 2^131991220 is an apocalyptic number.

131991220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

131991220 is an abundant number, since it is smaller than the sum of its proper divisors (145190384).

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

131991220 is a wasteful number, since it uses less digits than its factorization.

131991220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6599570 (or 6599568 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 131991220 is about 11488.7431862672. The cubic root of 131991220 is about 509.1530476680.

The spelling of 131991220 in words is "one hundred thirty-one million, nine hundred ninety-one thousand, two hundred twenty".