668378531 has 2 divisors, whose sum is σ = 668378532. Its totient is φ = 668378530.

The previous prime is 668378527. The next prime is 668378539. The reversal of 668378531 is 135873866.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 668378531 - 2² = 668378527 is a prime.

It is a super-2 number, since 2×668378531² = 893459721403435922, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (668378539) 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 as a sum of consecutive naturals, namely, 334189265 + 334189266.

It is an arithmetic number, because the mean of its divisors is an integer number (334189266).

Almost surely, 2^668378531 is an apocalyptic number.

668378531 is a deficient number, since it is larger than the sum of its proper divisors (1).

668378531 is an equidigital number, since it uses as much as digits as its factorization.

668378531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 47.

The square root of 668378531 is about 25853.0178315801. The cubic root of 668378531 is about 874.3275512653.

The spelling of 668378531 in words is "six hundred sixty-eight million, three hundred seventy-eight thousand, five hundred thirty-one".