1556660616661 has 16 divisors (see below), whose sum is σ = 1579486507200. Its totient is φ = 1534013251200.

The previous prime is 1556660616619. The next prime is 1556660616689. The reversal of 1556660616661 is 1666160666551.

It is a cyclic number.

It is not a de Polignac number, because 1556660616661 - 2³³ = 1548070682069 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 (1556660616601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35639686 + ... + 35683336.

It is an arithmetic number, because the mean of its divisors is an integer number (98717906700).

Almost surely, 2^{1556660616661} is an apocalyptic number.

It is an amenable number.

1556660616661 is a deficient number, since it is larger than the sum of its proper divisors (22825890539).

1556660616661 is a wasteful number, since it uses less digits than its factorization.

1556660616661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45684.

The product of its (nonzero) digits is 6998400, while the sum is 55.

The spelling of 1556660616661 in words is "one trillion, five hundred fifty-six billion, six hundred sixty million, six hundred sixteen thousand, six hundred sixty-one".