16604641881 has 9 divisors (see below), whose sum is σ = 23985041119. Its totient is φ = 11069503536.

The previous prime is 16604641849. The next prime is 16604641903. The reversal of 16604641881 is 18814640661.

The square root of 16604641881 is 128859.

It is a perfect power (a square), and thus also a powerful number.

16604641881 is a `hidden beast` number, since 1 + 6 + 6 + 0 + 464 + 188 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 933608025 + 15671033856 = 30555^2 + 125184^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 16604641881 - 2⁵ = 16604641849 is a prime.

It is a super-2 number, since 2×16604641881² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16604641841) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 365101 + ... + 408053.

Almost surely, 2^16604641881 is an apocalyptic number.

16604641881 is the 128859-th square number.

16604641881 is the 64430-th centered octagonal number.

It is an amenable number.

16604641881 is a deficient number, since it is larger than the sum of its proper divisors (7380399238).

16604641881 is an frugal number, since it uses more digits than its factorization.

16604641881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85912 (or 42956 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The spelling of 16604641881 in words is "sixteen billion, six hundred four million, six hundred forty-one thousand, eight hundred eighty-one".