668438429 has 6 divisors (see below), whose sum is σ = 691632090. Its totient is φ = 645254400.

The previous prime is 668438389. The next prime is 668438437. The reversal of 668438429 is 924834866.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 144120025 + 524318404 = 12005^2 + 22898^2 .

It is not a de Polignac number, because 668438429 - 2²⁸ = 400002973 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 (668438479) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 136829 + ... + 141629.

It is an arithmetic number, because the mean of its divisors is an integer number (115272015).

Almost surely, 2^668438429 is an apocalyptic number.

It is an amenable number.

668438429 is a deficient number, since it is larger than the sum of its proper divisors (23193661).

668438429 is an frugal number, since it uses more digits than its factorization.

668438429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9631 (or 4830 counting only the distinct ones).

The product of its digits is 1990656, while the sum is 50.

The square root of 668438429 is about 25854.1762390528. The cubic root of 668438429 is about 874.3536686548.

The spelling of 668438429 in words is "six hundred sixty-eight million, four hundred thirty-eight thousand, four hundred twenty-nine".