661731317 has 16 divisors (see below), whose sum is σ = 720720000. Its totient is φ = 603941184.

The previous prime is 661731299. The next prime is 661731337. The reversal of 661731317 is 713137166.

It is a cyclic number.

It is not a de Polignac number, because 661731317 - 2⁶ = 661731253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661731337) 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 15 ways as a sum of consecutive naturals, for example, 462359 + ... + 463787.

It is an arithmetic number, because the mean of its divisors is an integer number (45045000).

Almost surely, 2^661731317 is an apocalyptic number.

It is an amenable number.

661731317 is a deficient number, since it is larger than the sum of its proper divisors (58988683).

661731317 is a wasteful number, since it uses less digits than its factorization.

661731317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1820.

The product of its digits is 15876, while the sum is 35.

The square root of 661731317 is about 25724.1387999676. The cubic root of 661731317 is about 871.4194106241.

The spelling of 661731317 in words is "six hundred sixty-one million, seven hundred thirty-one thousand, three hundred seventeen".