2021820 has 48 divisors (see below), whose sum is σ = 5849088. Its totient is φ = 521280.

The previous prime is 2021807. The next prime is 2021837. The reversal of 2021820 is 281202.

2021820 = T₁₁₅ + T₁₁₆ + ... + T₂₃₈.

It is a super-2 number, since 2×2021820² = 8175512224800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 2021820.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1317 + ... + 2403.

It is an arithmetic number, because the mean of its divisors is an integer number (121856).

2^2021820 is an apocalyptic number.

2021820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2021820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2924544).

2021820 is an abundant number, since it is smaller than the sum of its proper divisors (3827268).

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

2021820 is a wasteful number, since it uses less digits than its factorization.

2021820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1130 (or 1128 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 2021820 is about 1421.9071699657. The cubic root of 2021820 is about 126.4486400157.

The spelling of 2021820 in words is "two million, twenty-one thousand, eight hundred twenty".