20109257 has 6 divisors (see below), whose sum is σ = 23392458. Its totient is φ = 17236464.

The previous prime is 20109233. The next prime is 20109263. The reversal of 20109257 is 75290102.

It can be written as a sum of positive squares in only one way, i.e., 19882681 + 226576 = 4459^2 + 476^2 .

It is not a de Polignac number, because 20109257 - 2²⁰ = 19060681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20109227) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 205148 + ... + 205245.

It is an arithmetic number, because the mean of its divisors is an integer number (3898743).

Almost surely, 2^20109257 is an apocalyptic number.

It is an amenable number.

20109257 is a deficient number, since it is larger than the sum of its proper divisors (3283201).

20109257 is an equidigital number, since it uses as much as digits as its factorization.

20109257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410407 (or 410400 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 20109257 is about 4484.3346217694. The cubic root of 20109257 is about 271.9351461945.

Adding to 20109257 its reverse (75290102), we get a palindrome (95399359).

The spelling of 20109257 in words is "twenty million, one hundred nine thousand, two hundred fifty-seven".