63891809 has 2 divisors, whose sum is σ = 63891810. Its totient is φ = 63891808.

The previous prime is 63891761. The next prime is 63891811. The reversal of 63891809 is 90819836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45427600 + 18464209 = 6740^2 + 4297^2 .

It is a cyclic number.

It is not a de Polignac number, because 63891809 - 2²⁰ = 62843233 is a prime.

Together with 63891811, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 63891809.

It is not a weakly prime, because it can be changed into another prime (63891829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31945904 + 31945905.

It is an arithmetic number, because the mean of its divisors is an integer number (31945905).

Almost surely, 2^63891809 is an apocalyptic number.

It is an amenable number.

63891809 is a deficient number, since it is larger than the sum of its proper divisors (1).

63891809 is an equidigital number, since it uses as much as digits as its factorization.

63891809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 44.

The square root of 63891809 is about 7993.2352023445. The cubic root of 63891809 is about 399.7744749534.

The spelling of 63891809 in words is "sixty-three million, eight hundred ninety-one thousand, eight hundred nine".