131820397 has 4 divisors (see below), whose sum is σ = 139574556. Its totient is φ = 124066240.

The previous prime is 131820391. The next prime is 131820439. The reversal of 131820397 is 793028131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 793028131 = 7 ⋅113289733.

It can be written as a sum of positive squares in 2 ways, for example, as 66113161 + 65707236 = 8131^2 + 8106^2 .

It is a cyclic number.

It is not a de Polignac number, because 131820397 - 2³ = 131820389 is a prime.

It is a nialpdrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131820391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3877054 + ... + 3877087.

It is an arithmetic number, because the mean of its divisors is an integer number (34893639).

Almost surely, 2^131820397 is an apocalyptic number.

131820397 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

131820397 is a deficient number, since it is larger than the sum of its proper divisors (7754159).

131820397 is an equidigital number, since it uses as much as digits as its factorization.

131820397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7754158.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 131820397 is about 11481.3064152125. The cubic root of 131820397 is about 508.9333042661.

The spelling of 131820397 in words is "one hundred thirty-one million, eight hundred twenty thousand, three hundred ninety-seven".