20091820 has 24 divisors (see below), whose sum is σ = 48220704. Its totient is φ = 6888576.

The previous prime is 20091803. The next prime is 20091847. The reversal of 20091820 is 2819002.

20091820 is nontrivially palindromic in base 9.

It is a junction number, because it is equal to n+sod(n) for n = 20091791 and 20091800.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71617 + ... + 71896.

It is an arithmetic number, because the mean of its divisors is an integer number (2009196).

Almost surely, 2^20091820 is an apocalyptic number.

20091820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20091820 is an abundant number, since it is smaller than the sum of its proper divisors (28128884).

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

20091820 is a wasteful number, since it uses less digits than its factorization.

20091820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143529 (or 143527 counting only the distinct ones).

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

The square root of 20091820 is about 4482.3899874955. The cubic root of 20091820 is about 271.8565239569.

The spelling of 20091820 in words is "twenty million, ninety-one thousand, eight hundred twenty".