661587393943 has 4 divisors (see below), whose sum is σ = 756099878800. Its totient is φ = 567074909088.

The previous prime is 661587393899. The next prime is 661587393979. The reversal of 661587393943 is 349393785166.

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-661587393943 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661587393043) 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, 47256242418 + ... + 47256242431.

It is an arithmetic number, because the mean of its divisors is an integer number (189024969700).

Almost surely, 2^661587393943 is an apocalyptic number.

661587393943 is a deficient number, since it is larger than the sum of its proper divisors (94512484857).

661587393943 is an equidigital number, since it uses as much as digits as its factorization.

661587393943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94512484856.

The product of its digits is 88179840, while the sum is 64.

The spelling of 661587393943 in words is "six hundred sixty-one billion, five hundred eighty-seven million, three hundred ninety-three thousand, nine hundred forty-three".