20105730 has 72 divisors (see below), whose sum is σ = 55602612. Its totient is φ = 5039616.

The previous prime is 20105711. The next prime is 20105731. The reversal of 20105730 is 3750102.

It can be written as a sum of positive squares in 6 ways, for example, as 9235521 + 10870209 = 3039^2 + 3297^2 .

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

It is not an unprimeable number, because it can be changed into a prime (20105731) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 25624 + ... + 26396.

Almost surely, 2^20105730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20105730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27801306).

20105730 is an abundant number, since it is smaller than the sum of its proper divisors (35496882).

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

20105730 is a wasteful number, since it uses less digits than its factorization.

20105730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 820 (or 800 counting only the distinct ones).

The product of its (nonzero) digits is 210, while the sum is 18.

The square root of 20105730 is about 4483.9413466280. The cubic root of 20105730 is about 271.9192468612.

Adding to 20105730 its reverse (3750102), we get a palindrome (23855832).

The spelling of 20105730 in words is "twenty million, one hundred five thousand, seven hundred thirty".