820639900 has 36 divisors (see below), whose sum is σ = 1796572512. Its totient is φ = 325346560.

The previous prime is 820639889. The next prime is 820639901. The reversal of 820639900 is 9936028.

It is a self number, because there is not a number n which added to its sum of digits gives 820639900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820639901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25012 + ... + 47611.

It is an arithmetic number, because the mean of its divisors is an integer number (49904792).

Almost surely, 2^820639900 is an apocalyptic number.

It is an amenable number.

820639900 is an abundant number, since it is smaller than the sum of its proper divisors (975932612).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

820639900 is a wasteful number, since it uses less digits than its factorization.

820639900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72750 (or 72743 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 820639900 is about 28646.8130862754. The cubic root of 820639900 is about 936.2335705966.

The spelling of 820639900 in words is "eight hundred twenty million, six hundred thirty-nine thousand, nine hundred".