821870920 has 32 divisors (see below), whose sum is σ = 1991457720. Its totient is φ = 303459840.

The previous prime is 821870869. The next prime is 821870923. The reversal of 821870920 is 29078128.

It can be written as a sum of positive squares in 4 ways, for example, as 517926564 + 303944356 = 22758^2 + 17434^2 .

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 821870920.

It is not an unprimeable number, because it can be changed into a prime (821870923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 789741 + ... + 790780.

Almost surely, 2^821870920 is an apocalyptic number.

It is an amenable number.

821870920 is an abundant number, since it is smaller than the sum of its proper divisors (1169586800).

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

821870920 is a wasteful number, since it uses less digits than its factorization.

821870920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1580545 (or 1580541 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 821870920 is about 28668.2911942794. The cubic root of 821870920 is about 936.7014763697.

The spelling of 821870920 in words is "eight hundred twenty-one million, eight hundred seventy thousand, nine hundred twenty".