15881120666 has 4 divisors (see below), whose sum is σ = 23821681002. Its totient is φ = 7940560332.

The previous prime is 15881120623. The next prime is 15881120681. The reversal of 15881120666 is 66602118851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66602118851 = 131 ⋅508413121.

It can be written as a sum of positive squares in only one way, i.e., 9755710441 + 6125410225 = 98771^2 + 78265^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3970280165 + ... + 3970280168.

Almost surely, 2^15881120666 is an apocalyptic number.

15881120666 is a deficient number, since it is larger than the sum of its proper divisors (7940560336).

15881120666 is an equidigital number, since it uses as much as digits as its factorization.

15881120666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7940560335.

The product of its (nonzero) digits is 138240, while the sum is 44.

The spelling of 15881120666 in words is "fifteen billion, eight hundred eighty-one million, one hundred twenty thousand, six hundred sixty-six".