669812391 has 24 divisors (see below), whose sum is σ = 1017300960. Its totient is φ = 424065600.

The previous prime is 669812383. The next prime is 669812459. The reversal of 669812391 is 193218966.

It is a happy number.

It is not a de Polignac number, because 669812391 - 2³ = 669812383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (669812321) 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 in 23 ways as a sum of consecutive naturals, for example, 5115 + ... + 36956.

It is an arithmetic number, because the mean of its divisors is an integer number (42387540).

Almost surely, 2^669812391 is an apocalyptic number.

669812391 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

669812391 is a deficient number, since it is larger than the sum of its proper divisors (347488569).

669812391 is a wasteful number, since it uses less digits than its factorization.

669812391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42167 (or 42164 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 669812391 is about 25880.7339733633. The cubic root of 669812391 is about 874.9523308997.

The spelling of 669812391 in words is "six hundred sixty-nine million, eight hundred twelve thousand, three hundred ninety-one".