640825469 has 2 divisors, whose sum is σ = 640825470. Its totient is φ = 640825468.

The previous prime is 640825457. The next prime is 640825477. The reversal of 640825469 is 964528046.

640825469 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 474673369 + 166152100 = 21787^2 + 12890^2 .

It is a cyclic number.

It is not a de Polignac number, because 640825469 - 2¹² = 640821373 is a prime.

It is a super-2 number, since 2×640825469² = 821314563438139922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640825429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320412734 + 320412735.

It is an arithmetic number, because the mean of its divisors is an integer number (320412735).

Almost surely, 2^640825469 is an apocalyptic number.

It is an amenable number.

640825469 is a deficient number, since it is larger than the sum of its proper divisors (1).

640825469 is an equidigital number, since it uses as much as digits as its factorization.

640825469 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 414720, while the sum is 44.

The square root of 640825469 is about 25314.5307876721. The cubic root of 640825469 is about 862.1442208039.

The spelling of 640825469 in words is "six hundred forty million, eight hundred twenty-five thousand, four hundred sixty-nine".