669999999 has 4 divisors (see below), whose sum is σ = 893333336. Its totient is φ = 446666664.

The previous prime is 669999989. The next prime is 670000013. The reversal of 669999999 is 999999966.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 669999999 - 2¹⁵ = 669967231 is a prime.

It is a Duffinian number.

669999999 is a modest number, since divided by 99999 gives 6699 as remainder.

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 669999999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (669999989) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111666664 + ... + 111666669.

It is an arithmetic number, because the mean of its divisors is an integer number (223333334).

Almost surely, 2^669999999 is an apocalyptic number.

669999999 is a deficient number, since it is larger than the sum of its proper divisors (223333337).

669999999 is a wasteful number, since it uses less digits than its factorization.

669999999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223333336.

The product of its digits is 172186884, while the sum is 75.

The square root of 669999999 is about 25884.3581917729. The cubic root of 669999999 is about 875.0340118480.

The spelling of 669999999 in words is "six hundred sixty-nine million, nine hundred ninety-nine thousand, nine hundred ninety-nine".