20018557 has 6 divisors (see below), whose sum is σ = 21677082. Its totient is φ = 18478512.

The previous prime is 20018543. The next prime is 20018567. The reversal of 20018557 is 75581002.

It can be written as a sum of positive squares in 3 ways, for example, as 1819801 + 18198756 = 1349^2 + 4266^2 .

It is not a de Polignac number, because 20018557 - 2⁷ = 20018429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20018527) 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, 59058 + ... + 59395.

It is an arithmetic number, because the mean of its divisors is an integer number (3612847).

Almost surely, 2^20018557 is an apocalyptic number.

It is an amenable number.

20018557 is a deficient number, since it is larger than the sum of its proper divisors (1658525).

20018557 is a wasteful number, since it uses less digits than its factorization.

20018557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118479 (or 118466 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 28.

The square root of 20018557 is about 4474.2102096348. The cubic root of 20018557 is about 271.5256881206.

Adding to 20018557 its reverse (75581002), we get a palindrome (95599559).

The spelling of 20018557 in words is "twenty million, eighteen thousand, five hundred fifty-seven".