131998721 has 8 divisors (see below), whose sum is σ = 138874344. Its totient is φ = 125297280.

The previous prime is 131998703. The next prime is 131998729. The reversal of 131998721 is 127899131.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6558721 + 125440000 = 2561^2 + 11200^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 131998721 - 2²⁶ = 64889857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (131998729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41990 + ... + 45023.

It is an arithmetic number, because the mean of its divisors is an integer number (17359293).

Almost surely, 2^131998721 is an apocalyptic number.

It is an amenable number.

131998721 is a deficient number, since it is larger than the sum of its proper divisors (6875623).

131998721 is an equidigital number, since it uses as much as digits as its factorization.

131998721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87091.

The product of its digits is 27216, while the sum is 41.

The square root of 131998721 is about 11489.0696316107. The cubic root of 131998721 is about 509.1626924627.

The spelling of 131998721 in words is "one hundred thirty-one million, nine hundred ninety-eight thousand, seven hundred twenty-one".