131906249721 has 9 divisors (see below), whose sum is σ = 190532823429. Its totient is φ = 87936773436.

The previous prime is 131906249719. The next prime is 131906249731. The reversal of 131906249721 is 127942609131.

The square root of 131906249721 is 363189.

It is a perfect power (a square), and thus also a powerful number.

131906249721 is a `hidden beast` number, since 1 + 3 + 19 + 0 + 624 + 9 + 7 + 2 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 131906249721 - 2¹ = 131906249719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (131906249731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1029036 + ... + 1150098.

Almost surely, 2^131906249721 is an apocalyptic number.

131906249721 is the 363189-th square number.

131906249721 is the 181595-th centered octagonal number.

It is an amenable number.

131906249721 is a deficient number, since it is larger than the sum of its proper divisors (58626573708).

131906249721 is an frugal number, since it uses more digits than its factorization.

131906249721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242132 (or 121066 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The spelling of 131906249721 in words is "one hundred thirty-one billion, nine hundred six million, two hundred forty-nine thousand, seven hundred twenty-one".