781664563 has 2 divisors, whose sum is σ = 781664564. Its totient is φ = 781664562.

The previous prime is 781664561. The next prime is 781664671. The reversal of 781664563 is 365466187.

781664563 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 781664563 - 2¹ = 781664561 is a prime.

It is a super-2 number, since 2×781664563² = 1221998978099961938, which contains 22 as substring.

Together with 781664561, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (781664561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390832281 + 390832282.

It is an arithmetic number, because the mean of its divisors is an integer number (390832282).

Almost surely, 2^781664563 is an apocalyptic number.

781664563 is a deficient number, since it is larger than the sum of its proper divisors (1).

781664563 is an equidigital number, since it uses as much as digits as its factorization.

781664563 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 46.

The square root of 781664563 is about 27958.2646636017. The cubic root of 781664563 is about 921.1707539227.

The spelling of 781664563 in words is "seven hundred eighty-one million, six hundred sixty-four thousand, five hundred sixty-three".