131681021 has 4 divisors (see below), whose sum is σ = 131723712. Its totient is φ = 131638332.

The previous prime is 131681009. The next prime is 131681027. The reversal of 131681021 is 120186131.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120186131 = 13 ⋅9245087.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131681021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131681027) 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, 16325 + ... + 23018.

It is an arithmetic number, because the mean of its divisors is an integer number (32930928).

Almost surely, 2^131681021 is an apocalyptic number.

It is an amenable number.

131681021 is a deficient number, since it is larger than the sum of its proper divisors (42691).

131681021 is an equidigital number, since it uses as much as digits as its factorization.

131681021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42690.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 131681021 is about 11475.2351174170. The cubic root of 131681021 is about 508.7538729992.

The spelling of 131681021 in words is "one hundred thirty-one million, six hundred eighty-one thousand, twenty-one".