820691638 has 16 divisors (see below), whose sum is σ = 1326283056. Its totient is φ = 378623520.

The previous prime is 820691587. The next prime is 820691687. The reversal of 820691638 is 836196028.

820691638 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 820691594 and 820691603.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77745 + ... + 87667.

It is an arithmetic number, because the mean of its divisors is an integer number (82892691).

Almost surely, 2^820691638 is an apocalyptic number.

820691638 is a deficient number, since it is larger than the sum of its proper divisors (505591418).

820691638 is a wasteful number, since it uses less digits than its factorization.

820691638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13119.

The product of its (nonzero) digits is 124416, while the sum is 43.

The square root of 820691638 is about 28647.7161044297. The cubic root of 820691638 is about 936.2532454197.

The spelling of 820691638 in words is "eight hundred twenty million, six hundred ninety-one thousand, six hundred thirty-eight".