661742758783 has 4 divisors (see below), whose sum is σ = 661744858968. Its totient is φ = 661740658600.

The previous prime is 661742758753. The next prime is 661742758811. The reversal of 661742758783 is 387857247166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661742758783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661742758753) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 471016 + ... + 1243117.

It is an arithmetic number, because the mean of its divisors is an integer number (165436214742).

Almost surely, 2^661742758783 is an apocalyptic number.

661742758783 is a deficient number, since it is larger than the sum of its proper divisors (2100185).

661742758783 is a wasteful number, since it uses less digits than its factorization.

661742758783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2100184.

The product of its digits is 94832640, while the sum is 64.

The spelling of 661742758783 in words is "six hundred sixty-one billion, seven hundred forty-two million, seven hundred fifty-eight thousand, seven hundred eighty-three".