820387643 has 16 divisors (see below), whose sum is σ = 892674720. Its totient is φ = 751286016.

The previous prime is 820387619. The next prime is 820387657. The reversal of 820387643 is 346783028.

It is a cyclic number.

It is not a de Polignac number, because 820387643 - 2¹² = 820383547 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 820387643.

It is not an unprimeable number, because it can be changed into a prime (820387693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 106655 + ... + 114087.

It is an arithmetic number, because the mean of its divisors is an integer number (55792170).

Almost surely, 2^820387643 is an apocalyptic number.

820387643 is a deficient number, since it is larger than the sum of its proper divisors (72287077).

820387643 is a wasteful number, since it uses less digits than its factorization.

820387643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7646.

The product of its (nonzero) digits is 193536, while the sum is 41.

The square root of 820387643 is about 28642.4098671882. The cubic root of 820387643 is about 936.1376309626.

The spelling of 820387643 in words is "eight hundred twenty million, three hundred eighty-seven thousand, six hundred forty-three".