667387729 has 2 divisors, whose sum is σ = 667387730. Its totient is φ = 667387728.

The previous prime is 667387727. The next prime is 667387781. The reversal of 667387729 is 927783766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 532363329 + 135024400 = 23073^2 + 11620^2 .

It is a cyclic number.

It is not a de Polignac number, because 667387729 - 2¹ = 667387727 is a prime.

Together with 667387727, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 667387729.

It is not a weakly prime, because it can be changed into another prime (667387727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333693864 + 333693865.

It is an arithmetic number, because the mean of its divisors is an integer number (333693865).

Almost surely, 2^667387729 is an apocalyptic number.

It is an amenable number.

667387729 is a deficient number, since it is larger than the sum of its proper divisors (1).

667387729 is an equidigital number, since it uses as much as digits as its factorization.

667387729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5334336, while the sum is 55.

The square root of 667387729 is about 25833.8485131426. The cubic root of 667387729 is about 873.8953042382.

The spelling of 667387729 in words is "six hundred sixty-seven million, three hundred eighty-seven thousand, seven hundred twenty-nine".