20491020 has 144 divisors (see below), whose sum is σ = 69189120. Its totient is φ = 4867200.

The previous prime is 20490997. The next prime is 20491039. The reversal of 20491020 is 2019402.

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 = 20490984 and 20491002.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 156355 + ... + 156485.

It is an arithmetic number, because the mean of its divisors is an integer number (480480).

Almost surely, 2^20491020 is an apocalyptic number.

20491020 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 20491020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34594560).

20491020 is an abundant number, since it is smaller than the sum of its proper divisors (48698100).

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

20491020 is a wasteful number, since it uses less digits than its factorization.

20491020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236 (or 231 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 20491020 is about 4526.7007853402. The cubic root of 20491020 is about 273.6452154163.

The spelling of 20491020 in words is "twenty million, four hundred ninety-one thousand, twenty".