20001020 has 48 divisors (see below), whose sum is σ = 46310880. Its totient is φ = 7209216.

The previous prime is 20001019. The next prime is 20001029. The reversal of 20001020 is 2010002.

It is a Harshad number since it is a multiple of its sum of digits (5).

It is a junction number, because it is equal to n+sod(n) for n = 20000995 and 20001013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10286 + ... + 12074.

It is an arithmetic number, because the mean of its divisors is an integer number (964810).

Almost surely, 2^20001020 is an apocalyptic number.

20001020 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 20001020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23155440).

20001020 is an abundant number, since it is smaller than the sum of its proper divisors (26309860).

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

20001020 is a wasteful number, since it uses less digits than its factorization.

20001020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1854 (or 1852 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 5.

The square root of 20001020 is about 4472.2499930125. The cubic root of 20001020 is about 271.4463760910.

Adding to 20001020 its reverse (2010002), we get a palindrome (22011022).

The spelling of 20001020 in words is "twenty million, one thousand, twenty".