669745778 has 16 divisors (see below), whose sum is σ = 1119205080. Its totient is φ = 298454016.

The previous prime is 669745771. The next prime is 669745859. The reversal of 669745778 is 877547966.

It can be written as a sum of positive squares in 4 ways, for example, as 315666289 + 354079489 = 17767^2 + 18817^2 .

It is not an unprimeable number, because it can be changed into a prime (669745771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 443375 + ... + 444882.

Almost surely, 2^669745778 is an apocalyptic number.

669745778 is a deficient number, since it is larger than the sum of its proper divisors (449459302).

669745778 is a wasteful number, since it uses less digits than its factorization.

669745778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888301.

The product of its digits is 17781120, while the sum is 59.

The square root of 669745778 is about 25879.4470188217. The cubic root of 669745778 is about 874.9233251997.

The spelling of 669745778 in words is "six hundred sixty-nine million, seven hundred forty-five thousand, seven hundred seventy-eight".