656736673661 has 4 divisors (see below), whose sum is σ = 664115737500. Its totient is φ = 649357609824.

The previous prime is 656736673643. The next prime is 656736673687. The reversal of 656736673661 is 166376637656.

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

It can be written as a sum of positive squares in 2 ways, for example, as 304476618436 + 352260055225 = 551794^2 + 593515^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-656736673661 is a prime.

It is a super-2 number, since 2×656736673661² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 656736673594 and 656736673603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656736673261) 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 3 ways as a sum of consecutive naturals, for example, 3689531786 + ... + 3689531963.

It is an arithmetic number, because the mean of its divisors is an integer number (166028934375).

Almost surely, 2^656736673661 is an apocalyptic number.

It is an amenable number.

656736673661 is a deficient number, since it is larger than the sum of its proper divisors (7379063839).

656736673661 is an equidigital number, since it uses as much as digits as its factorization.

656736673661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7379063838.

The product of its digits is 102876480, while the sum is 62.

The spelling of 656736673661 in words is "six hundred fifty-six billion, seven hundred thirty-six million, six hundred seventy-three thousand, six hundred sixty-one".