1777665985 has 4 divisors (see below), whose sum is σ = 2133199188. Its totient is φ = 1422132784.

The previous prime is 1777665977. The next prime is 1777666039. The reversal of 1777665985 is 5895667771.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5895667771 = 7 ⋅842238253.

It can be written as a sum of positive squares in 2 ways, for example, as 561121344 + 1216544641 = 23688^2 + 34879^2 .

It is a cyclic number.

It is not a de Polignac number, because 1777665985 - 2³ = 1777665977 is a prime.

It is a Duffinian 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, 177766594 + ... + 177766603.

It is an arithmetic number, because the mean of its divisors is an integer number (533299797).

Almost surely, 2^1777665985 is an apocalyptic number.

It is an amenable number.

1777665985 is a deficient number, since it is larger than the sum of its proper divisors (355533203).

1777665985 is an equidigital number, since it uses as much as digits as its factorization.

1777665985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355533202.

The product of its digits is 22226400, while the sum is 61.

The square root of 1777665985 is about 42162.3764154726. The cubic root of 1777665985 is about 1211.3883354027.

The spelling of 1777665985 in words is "one billion, seven hundred seventy-seven million, six hundred sixty-five thousand, nine hundred eighty-five".