646138693 has 2 divisors, whose sum is σ = 646138694. Its totient is φ = 646138692.

The previous prime is 646138667. The next prime is 646138699. The reversal of 646138693 is 396831646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 613156644 + 32982049 = 24762^2 + 5743^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646138693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646138699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323069346 + 323069347.

It is an arithmetic number, because the mean of its divisors is an integer number (323069347).

Almost surely, 2^646138693 is an apocalyptic number.

It is an amenable number.

646138693 is a deficient number, since it is larger than the sum of its proper divisors (1).

646138693 is an equidigital number, since it uses as much as digits as its factorization.

646138693 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 559872, while the sum is 46.

The square root of 646138693 is about 25419.2583094000. The cubic root of 646138693 is about 864.5204077373.

It can be divided in two parts, 6461 and 38693, that added together give a palindrome (45154).

The spelling of 646138693 in words is "six hundred forty-six million, one hundred thirty-eight thousand, six hundred ninety-three".