643459769 has 4 divisors (see below), whose sum is σ = 643646244. Its totient is φ = 643273296.

The previous prime is 643459763. The next prime is 643459787. The reversal of 643459769 is 967954346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 967954346 = 2 ⋅483977173.

It can be written as a sum of positive squares in 2 ways, for example, as 585882025 + 57577744 = 24205^2 + 7588^2 .

It is a cyclic number.

It is not a de Polignac number, because 643459769 - 2⁸ = 643459513 is a prime.

It is a super-2 number, since 2×643459769² = 828080948643066722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 643459769.

It is not an unprimeable number, because it can be changed into a prime (643459763) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 87962 + ... + 94995.

It is an arithmetic number, because the mean of its divisors is an integer number (160911561).

Almost surely, 2^643459769 is an apocalyptic number.

It is an amenable number.

643459769 is a deficient number, since it is larger than the sum of its proper divisors (186475).

643459769 is a wasteful number, since it uses less digits than its factorization.

643459769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186474.

The product of its digits is 4898880, while the sum is 53.

The square root of 643459769 is about 25366.5088059039. The cubic root of 643459769 is about 863.3239708026.

The spelling of 643459769 in words is "six hundred forty-three million, four hundred fifty-nine thousand, seven hundred sixty-nine".