639974121769 has 2 divisors, whose sum is σ = 639974121770. Its totient is φ = 639974121768.

The previous prime is 639974121757. The next prime is 639974121781. The reversal of 639974121769 is 967121479936.

It is a balanced prime because it is at equal distance from previous prime (639974121757) and next prime (639974121781).

It can be written as a sum of positive squares in only one way, i.e., 420915488400 + 219058633369 = 648780^2 + 468037^2 .

It is a cyclic number.

It is not a de Polignac number, because 639974121769 - 2¹⁹ = 639973597481 is a prime.

It is a super-2 number, since 2×639974121769² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 639974121769.

It is not a weakly prime, because it can be changed into another prime (639974121749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319987060884 + 319987060885.

It is an arithmetic number, because the mean of its divisors is an integer number (319987060885).

Almost surely, 2^639974121769 is an apocalyptic number.

It is an amenable number.

639974121769 is a deficient number, since it is larger than the sum of its proper divisors (1).

639974121769 is an equidigital number, since it uses as much as digits as its factorization.

639974121769 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30862944, while the sum is 64.

The spelling of 639974121769 in words is "six hundred thirty-nine billion, nine hundred seventy-four million, one hundred twenty-one thousand, seven hundred sixty-nine".