669999989 has 2 divisors, whose sum is σ = 669999990. Its totient is φ = 669999988.

The previous prime is 669999961. The next prime is 670000013. The reversal of 669999989 is 989999966.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 623351089 + 46648900 = 24967^2 + 6830^2 .

It is a cyclic number.

It is not a de Polignac number, because 669999989 - 2²⁸ = 401564533 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (669999089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334999994 + 334999995.

It is an arithmetic number, because the mean of its divisors is an integer number (334999995).

Almost surely, 2^669999989 is an apocalyptic number.

It is an amenable number.

669999989 is a deficient number, since it is larger than the sum of its proper divisors (1).

669999989 is an equidigital number, since it uses as much as digits as its factorization.

669999989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 153055008, while the sum is 74.

The square root of 669999989 is about 25884.3579986060. The cubic root of 669999989 is about 875.0340074946.

The spelling of 669999989 in words is "six hundred sixty-nine million, nine hundred ninety-nine thousand, nine hundred eighty-nine".