20001820 has 24 divisors (see below), whose sum is σ = 43360128. Its totient is φ = 7742400.

The previous prime is 20001811. The next prime is 20001823. The reversal of 20001820 is 2810002.

20001820 is a modest number, since divided by 1820 gives 20 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 20001820.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15511 + ... + 16750.

It is an arithmetic number, because the mean of its divisors is an integer number (1806672).

Almost surely, 2^20001820 is an apocalyptic number.

20001820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20001820 is an abundant number, since it is smaller than the sum of its proper divisors (23358308).

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

20001820 is a wasteful number, since it uses less digits than its factorization.

20001820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32301 (or 32299 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 20001820 is about 4472.3394325565. The cubic root of 20001820 is about 271.4499951432.

Adding to 20001820 its reverse (2810002), we get a palindrome (22811822).

The spelling of 20001820 in words is "twenty million, one thousand, eight hundred twenty".