1821980 has 12 divisors (see below), whose sum is σ = 3826200. Its totient is φ = 728784.

The previous prime is 1821959. The next prime is 1821997. The reversal of 1821980 is 891281.

It is a super-2 number, since 2×1821980² = 6639222240800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45530 + ... + 45569.

It is an arithmetic number, because the mean of its divisors is an integer number (318850).

2^1821980 is an apocalyptic number.

1821980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1821980 is an abundant number, since it is smaller than the sum of its proper divisors (2004220).

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

1821980 is a wasteful number, since it uses less digits than its factorization.

1821980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91108 (or 91106 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 29.

The square root of 1821980 is about 1349.8073936677. The cubic root of 1821980 is about 122.1371743811.

The spelling of 1821980 in words is "one million, eight hundred twenty-one thousand, nine hundred eighty".