667556389 has 2 divisors, whose sum is σ = 667556390. Its totient is φ = 667556388.

The previous prime is 667556377. The next prime is 667556411. The reversal of 667556389 is 983655766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 459244900 + 208311489 = 21430^2 + 14433^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-667556389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667556189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333778194 + 333778195.

It is an arithmetic number, because the mean of its divisors is an integer number (333778195).

Almost surely, 2^667556389 is an apocalyptic number.

It is an amenable number.

667556389 is a deficient number, since it is larger than the sum of its proper divisors (1).

667556389 is an equidigital number, since it uses as much as digits as its factorization.

667556389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8164800, while the sum is 55.

The square root of 667556389 is about 25837.1126289297. The cubic root of 667556389 is about 873.9689140062.

The spelling of 667556389 in words is "six hundred sixty-seven million, five hundred fifty-six thousand, three hundred eighty-nine".