20891020 has 48 divisors (see below), whose sum is σ = 45864000. Its totient is φ = 7983360.

The previous prime is 20891009. The next prime is 20891027. The reversal of 20891020 is 2019802.

It is a junction number, because it is equal to n+sod(n) for n = 20890982 and 20891000.

It is not an unprimeable number, because it can be changed into a prime (20891027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 104881 + ... + 105079.

It is an arithmetic number, because the mean of its divisors is an integer number (955500).

Almost surely, 2^20891020 is an apocalyptic number.

20891020 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 20891020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22932000).

20891020 is an abundant number, since it is smaller than the sum of its proper divisors (24972980).

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

20891020 is a wasteful number, since it uses less digits than its factorization.

20891020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 418 (or 416 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 20891020 is about 4570.6695351994. The cubic root of 20891020 is about 275.4143395927.

The spelling of 20891020 in words is "twenty million, eight hundred ninety-one thousand, twenty".