668367421 has 2 divisors, whose sum is σ = 668367422. Its totient is φ = 668367420.

The previous prime is 668367383. The next prime is 668367439. The reversal of 668367421 is 124763866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 388641796 + 279725625 = 19714^2 + 16725^2 .

It is a cyclic number.

It is not a de Polignac number, because 668367421 - 2²⁵ = 634812989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668367221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334183710 + 334183711.

It is an arithmetic number, because the mean of its divisors is an integer number (334183711).

Almost surely, 2^668367421 is an apocalyptic number.

It is an amenable number.

668367421 is a deficient number, since it is larger than the sum of its proper divisors (1).

668367421 is an equidigital number, since it uses as much as digits as its factorization.

668367421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 290304, while the sum is 43.

The square root of 668367421 is about 25852.8029621548. The cubic root of 668367421 is about 874.3227067884.

The spelling of 668367421 in words is "six hundred sixty-eight million, three hundred sixty-seven thousand, four hundred twenty-one".