131721665 has 16 divisors (see below), whose sum is σ = 164776512. Its totient is φ = 100989504.

The previous prime is 131721641. The next prime is 131721671. The reversal of 131721665 is 566127131.

It is a cyclic number.

It is not a de Polignac number, because 131721665 - 2⁸ = 131721409 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7082 + ... + 17708.

It is an arithmetic number, because the mean of its divisors is an integer number (10298532).

Almost surely, 2^131721665 is an apocalyptic number.

It is an amenable number.

131721665 is a deficient number, since it is larger than the sum of its proper divisors (33054847).

131721665 is a wasteful number, since it uses less digits than its factorization.

131721665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10736.

The product of its digits is 7560, while the sum is 32.

The square root of 131721665 is about 11477.0059248917. The cubic root of 131721665 is about 508.8062107499.

Adding to 131721665 its reverse (566127131), we get a palindrome (697848796).

The spelling of 131721665 in words is "one hundred thirty-one million, seven hundred twenty-one thousand, six hundred sixty-five".