2021821820 has 24 divisors (see below), whose sum is σ = 4315432128. Its totient is φ = 795470400.

The previous prime is 2021821819. The next prime is 2021821871. The reversal of 2021821820 is 281281202.

It is a super-2 number, since 2×2021821820² = 8175526943656224800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 2021821820.

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, 827396 + ... + 829835.

It is an arithmetic number, because the mean of its divisors is an integer number (179809672).

Almost surely, 2^2021821820 is an apocalyptic number.

2021821820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2021821820 is an abundant number, since it is smaller than the sum of its proper divisors (2293610308).

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

2021821820 is a wasteful number, since it uses less digits than its factorization.

2021821820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1657301 (or 1657299 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 2021821820 is about 44964.6730222738. The cubic root of 2021821820 is about 1264.4867795780.

The spelling of 2021821820 in words is "two billion, twenty-one million, eight hundred twenty-one thousand, eight hundred twenty".