665463989 has 4 divisors (see below), whose sum is σ = 681694860. Its totient is φ = 649233120.

The previous prime is 665463983. The next prime is 665464021. The reversal of 665463989 is 989364566.

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

It can be written as a sum of positive squares in 2 ways, for example, as 38812900 + 626651089 = 6230^2 + 25033^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665463989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665463983) 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, 8115374 + ... + 8115455.

It is an arithmetic number, because the mean of its divisors is an integer number (170423715).

Almost surely, 2^665463989 is an apocalyptic number.

It is an amenable number.

665463989 is a deficient number, since it is larger than the sum of its proper divisors (16230871).

665463989 is a wasteful number, since it uses less digits than its factorization.

665463989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16230870.

The product of its digits is 8398080, while the sum is 56.

The square root of 665463989 is about 25796.5887085870. The cubic root of 665463989 is about 873.0548306678.

The spelling of 665463989 in words is "six hundred sixty-five million, four hundred sixty-three thousand, nine hundred eighty-nine".