1638666313 has 2 divisors, whose sum is σ = 1638666314. Its totient is φ = 1638666312.

The previous prime is 1638666287. The next prime is 1638666347. The reversal of 1638666313 is 3136668361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1638387529 + 278784 = 40477^2 + 528^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1638666313 is a prime.

It is a super-2 number, since 2×1638666313² = 5370454570722027938, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1638666313.

It is not a weakly prime, because it can be changed into another prime (1638666383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819333156 + 819333157.

It is an arithmetic number, because the mean of its divisors is an integer number (819333157).

Almost surely, 2^1638666313 is an apocalyptic number.

It is an amenable number.

1638666313 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638666313 is an equidigital number, since it uses as much as digits as its factorization.

1638666313 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 279936, while the sum is 43.

The square root of 1638666313 is about 40480.4435869964. The cubic root of 1638666313 is about 1178.9539501592.

The spelling of 1638666313 in words is "one billion, six hundred thirty-eight million, six hundred sixty-six thousand, three hundred thirteen".