668649061 has 4 divisors (see below), whose sum is σ = 669210732. Its totient is φ = 668087392.

The previous prime is 668649053. The next prime is 668649071. The reversal of 668649061 is 160946866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 160946866 = 2 ⋅80473433.

It can be written as a sum of positive squares in 2 ways, for example, as 220522500 + 448126561 = 14850^2 + 21169^2 .

It is a cyclic number.

It is not a de Polignac number, because 668649061 - 2³ = 668649053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668649001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 279046 + ... + 281431.

It is an arithmetic number, because the mean of its divisors is an integer number (167302683).

Almost surely, 2^668649061 is an apocalyptic number.

It is an amenable number.

668649061 is a deficient number, since it is larger than the sum of its proper divisors (561671).

668649061 is a wasteful number, since it uses less digits than its factorization.

668649061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 561670.

The product of its (nonzero) digits is 373248, while the sum is 46.

The square root of 668649061 is about 25858.2493800334. The cubic root of 668649061 is about 874.4454983647.

The spelling of 668649061 in words is "six hundred sixty-eight million, six hundred forty-nine thousand, sixty-one".