663669391 has 12 divisors (see below), whose sum is σ = 833701456. Its totient is φ = 517144320.

The previous prime is 663669329. The next prime is 663669397. The reversal of 663669391 is 193966366.

It is not a de Polignac number, because 663669391 - 2¹⁹ = 663145103 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663669397) 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 11 ways as a sum of consecutive naturals, for example, 390930 + ... + 392623.

Almost surely, 2^663669391 is an apocalyptic number.

663669391 is a deficient number, since it is larger than the sum of its proper divisors (170032065).

663669391 is a wasteful number, since it uses less digits than its factorization.

663669391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 783582 (or 783571 counting only the distinct ones).

The product of its digits is 944784, while the sum is 49.

The square root of 663669391 is about 25761.7815959999. The cubic root of 663669391 is about 872.2693170984.

It can be divided in two parts, 66366 and 9391, that added together give a palindrome (75757).

The spelling of 663669391 in words is "six hundred sixty-three million, six hundred sixty-nine thousand, three hundred ninety-one".