16556313661 has 8 divisors (see below), whose sum is σ = 16581660984. Its totient is φ = 16530984960.

The previous prime is 16556313647. The next prime is 16556313667. The reversal of 16556313661 is 16631365561.

It can be written as a sum of positive squares in 4 ways, for example, as 2205711225 + 14350602436 = 46965^2 + 119794^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16556313661 - 2⁷ = 16556313533 is a prime.

It is a super-2 number, since 2×16556313661² (a number of 21 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 (16556313667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3692541 + ... + 3697021.

It is an arithmetic number, because the mean of its divisors is an integer number (2072707623).

Almost surely, 2^16556313661 is an apocalyptic number.

It is an amenable number.

16556313661 is a deficient number, since it is larger than the sum of its proper divisors (25347323).

16556313661 is an equidigital number, since it uses as much as digits as its factorization.

16556313661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9311.

The product of its digits is 291600, while the sum is 43.

The spelling of 16556313661 in words is "sixteen billion, five hundred fifty-six million, three hundred thirteen thousand, six hundred sixty-one".