661667623 has 2 divisors, whose sum is σ = 661667624. Its totient is φ = 661667622.

The previous prime is 661667599. The next prime is 661667641. The reversal of 661667623 is 326766166.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661667623 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661667623.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661667653) 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, 330833811 + 330833812.

It is an arithmetic number, because the mean of its divisors is an integer number (330833812).

Almost surely, 2^661667623 is an apocalyptic number.

661667623 is a deficient number, since it is larger than the sum of its proper divisors (1).

661667623 is an equidigital number, since it uses as much as digits as its factorization.

661667623 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 43.

The square root of 661667623 is about 25722.9007501098. The cubic root of 661667623 is about 871.3914506513.

The spelling of 661667623 in words is "six hundred sixty-one million, six hundred sixty-seven thousand, six hundred twenty-three".