690655778 has 6 divisors (see below), whose sum is σ = 1036039419. Its totient is φ = 345309306.

The previous prime is 690655759. The next prime is 690655781. The reversal of 690655778 is 877556096.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 345327889 + 345327889 = 18583^2 + 18583^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=18583.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 27875 + ... + 46457.

Almost surely, 2^690655778 is an apocalyptic number.

690655778 is a deficient number, since it is larger than the sum of its proper divisors (345383641).

690655778 is an frugal number, since it uses more digits than its factorization.

690655778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37168 (or 18585 counting only the distinct ones).

The product of its (nonzero) digits is 3175200, while the sum is 53.

The square root of 690655778 is about 26280.3306295792. The cubic root of 690655778 is about 883.9354465464.

The spelling of 690655778 in words is "six hundred ninety million, six hundred fifty-five thousand, seven hundred seventy-eight".