661184357991 has 8 divisors (see below), whose sum is σ = 881586330240. Its totient is φ = 440785978872.

The previous prime is 661184357983. The next prime is 661184358001. The reversal of 661184357991 is 199753481166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661184357991 - 2³ = 661184357983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661184357941) 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, 434745 + ... + 1229378.

It is an arithmetic number, because the mean of its divisors is an integer number (110198291280).

Almost surely, 2^661184357991 is an apocalyptic number.

661184357991 is a deficient number, since it is larger than the sum of its proper divisors (220401972249).

661184357991 is a wasteful number, since it uses less digits than its factorization.

661184357991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1796565.

The product of its digits is 9797760, while the sum is 60.

The spelling of 661184357991 in words is "six hundred sixty-one billion, one hundred eighty-four million, three hundred fifty-seven thousand, nine hundred ninety-one".