668399042 has 4 divisors (see below), whose sum is σ = 1002598566. Its totient is φ = 334199520.

The previous prime is 668399027. The next prime is 668399057. The reversal of 668399042 is 240993866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 240993866 = 2 ⋅120496933.

It is an interprime number because it is at equal distance from previous prime (668399027) and next prime (668399057).

It can be written as a sum of positive squares in only one way, i.e., 465308041 + 203091001 = 21571^2 + 14251^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167099759 + ... + 167099762.

Almost surely, 2^668399042 is an apocalyptic number.

668399042 is a deficient number, since it is larger than the sum of its proper divisors (334199524).

668399042 is a wasteful number, since it uses less digits than its factorization.

668399042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334199523.

The product of its (nonzero) digits is 559872, while the sum is 47.

The square root of 668399042 is about 25853.4145133675. The cubic root of 668399042 is about 874.3364948744.

The spelling of 668399042 in words is "six hundred sixty-eight million, three hundred ninety-nine thousand, forty-two".