661712672491 has 8 divisors (see below), whose sum is σ = 716194623200. Its totient is φ = 607742289792.

The previous prime is 661712672483. The next prime is 661712672507. The reversal of 661712672491 is 194276217166.

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 661712672491 - 2³ = 661712672483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661712672431) 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, 127889310 + ... + 127894483.

It is an arithmetic number, because the mean of its divisors is an integer number (89524327900).

Almost surely, 2^661712672491 is an apocalyptic number.

661712672491 is a deficient number, since it is larger than the sum of its proper divisors (54481950709).

661712672491 is a wasteful number, since it uses less digits than its factorization.

661712672491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255784005.

The product of its digits is 1524096, while the sum is 52.

The spelling of 661712672491 in words is "six hundred sixty-one billion, seven hundred twelve million, six hundred seventy-two thousand, four hundred ninety-one".