20842020 has 72 divisors (see below), whose sum is σ = 63980280. Its totient is φ = 5491200.

The previous prime is 20842007. The next prime is 20842021. The reversal of 20842020 is 2024802.

It can be written as a sum of positive squares in 4 ways, for example, as 968256 + 19873764 = 984^2 + 4458^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20841984 and 20842002.

It is not an unprimeable number, because it can be changed into a prime (20842021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15370 + ... + 16670.

It is an arithmetic number, because the mean of its divisors is an integer number (888615).

Almost surely, 2^20842020 is an apocalyptic number.

20842020 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 20842020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31990140).

20842020 is an abundant number, since it is smaller than the sum of its proper divisors (43138260).

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

20842020 is a wasteful number, since it uses less digits than its factorization.

20842020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1405 (or 1400 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 20842020 is about 4565.3061233613. The cubic root of 20842020 is about 275.1988424156.

Adding to 20842020 its reverse (2024802), we get a palindrome (22866822).

The spelling of 20842020 in words is "twenty million, eight hundred forty-two thousand, twenty".