61556615656661 has 4 divisors (see below), whose sum is σ = 62298261628512. Its totient is φ = 60814969684812.

The previous prime is 61556615656651. The next prime is 61556615656667. The reversal of 61556615656661 is 16665651665516.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 61556615656661 - 2¹⁸ = 61556615394517 is a prime.

It is a super-2 number, since 2×61556615656661² (a number of 28 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61556615656667) 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, 370822985801 + ... + 370822985966.

It is an arithmetic number, because the mean of its divisors is an integer number (15574565407128).

Almost surely, 2^{61556615656661} is an apocalyptic number.

It is an amenable number.

61556615656661 is a deficient number, since it is larger than the sum of its proper divisors (741645971851).

61556615656661 is an equidigital number, since it uses as much as digits as its factorization.

61556615656661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 741645971850.

The product of its digits is 174960000, while the sum is 65.

The spelling of 61556615656661 in words is "sixty-one trillion, five hundred fifty-six billion, six hundred fifteen million, six hundred fifty-six thousand, six hundred sixty-one".