2021921820 has 36 divisors (see below), whose sum is σ = 6133163400. Its totient is φ = 539179104.

The previous prime is 2021921819. The next prime is 2021921851. The reversal of 2021921820 is 281291202.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×2021921820² = 8176335692384224800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5616270 + ... + 5616629.

It is an arithmetic number, because the mean of its divisors is an integer number (170365650).

Almost surely, 2^2021921820 is an apocalyptic number.

2021921820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2021921820 is an abundant number, since it is smaller than the sum of its proper divisors (4111241580).

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

2021921820 is a wasteful number, since it uses less digits than its factorization.

2021921820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11232914 (or 11232909 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 2021921820 is about 44965.7849925919. The cubic root of 2021921820 is about 1264.5076265507.

The spelling of 2021921820 in words is "two billion, twenty-one million, nine hundred twenty-one thousand, eight hundred twenty".