820921000 has 32 divisors (see below), whose sum is σ = 1920957480. Its totient is φ = 328368000.

The previous prime is 820920979. The next prime is 820921001. The reversal of 820921000 is 129028.

It can be written as a sum of positive squares in 4 ways, for example, as 143568324 + 677352676 = 11982^2 + 26026^2 .

It is a super-2 number, since 2×820921000² = 1347822576482000000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (820921001) 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, 409461 + ... + 411460.

Almost surely, 2^820921000 is an apocalyptic number.

It is an amenable number.

820921000 is an abundant number, since it is smaller than the sum of its proper divisors (1100036480).

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

820921000 is a wasteful number, since it uses less digits than its factorization.

820921000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 820942 (or 820928 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 820921000 is about 28651.7189711193. The cubic root of 820921000 is about 936.3404567852.

The spelling of 820921000 in words is "eight hundred twenty million, nine hundred twenty-one thousand".