1666777885 has 4 divisors (see below), whose sum is σ = 2000133468. Its totient is φ = 1333422304.

The previous prime is 1666777859. The next prime is 1666777919. The reversal of 1666777885 is 5887776661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5887776661 = 13 ⋅452905897.

It can be written as a sum of positive squares in 2 ways, for example, as 1136903524 + 529874361 = 33718^2 + 23019^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666777885 - 2²³ = 1658389277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166677784 + ... + 166677793.

It is an arithmetic number, because the mean of its divisors is an integer number (500033367).

Almost surely, 2^1666777885 is an apocalyptic number.

It is an amenable number.

1666777885 is a deficient number, since it is larger than the sum of its proper divisors (333355583).

1666777885 is an equidigital number, since it uses as much as digits as its factorization.

1666777885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333355582.

The product of its digits is 23708160, while the sum is 61.

The square root of 1666777885 is about 40826.1911644964. The cubic root of 1666777885 is about 1185.6574736931.

The spelling of 1666777885 in words is "one billion, six hundred sixty-six million, seven hundred seventy-seven thousand, eight hundred eighty-five".