17666481981 has 4 divisors (see below), whose sum is σ = 23555309312. Its totient is φ = 11777654652.

The previous prime is 17666481977. The next prime is 17666482039. The reversal of 17666481981 is 18918466671.

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 not a de Polignac number, because 17666481981 - 2² = 17666481977 is a prime.

It is a super-2 number, since 2×17666481981² (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 (17666481961) 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, 2944413661 + ... + 2944413666.

It is an arithmetic number, because the mean of its divisors is an integer number (5888827328).

Almost surely, 2^17666481981 is an apocalyptic number.

It is an amenable number.

17666481981 is a deficient number, since it is larger than the sum of its proper divisors (5888827331).

17666481981 is an equidigital number, since it uses as much as digits as its factorization.

17666481981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5888827330.

The product of its digits is 3483648, while the sum is 57.

The spelling of 17666481981 in words is "seventeen billion, six hundred sixty-six million, four hundred eighty-one thousand, nine hundred eighty-one".