661759967993 has 16 divisors (see below), whose sum is σ = 686860611840. Its totient is φ = 637164176256.

The previous prime is 661759967977. The next prime is 661759968007. The reversal of 661759967993 is 399769957166.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 661759967993 - 2⁴ = 661759967977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661759967923) 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 15 ways as a sum of consecutive naturals, for example, 1086746 + ... + 1582572.

It is an arithmetic number, because the mean of its divisors is an integer number (42928788240).

Almost surely, 2^661759967993 is an apocalyptic number.

It is an amenable number.

661759967993 is a deficient number, since it is larger than the sum of its proper divisors (25100643847).

661759967993 is a wasteful number, since it uses less digits than its factorization.

661759967993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 496336.

The product of its digits is 1041624360, while the sum is 77.

The spelling of 661759967993 in words is "six hundred sixty-one billion, seven hundred fifty-nine million, nine hundred sixty-seven thousand, nine hundred ninety-three".