20118557 has 4 divisors (see below), whose sum is σ = 20145756. Its totient is φ = 20091360.

The previous prime is 20118551. The next prime is 20118617. The reversal of 20118557 is 75581102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6421156 + 13697401 = 2534^2 + 3701^2 .

It is a cyclic number.

It is not a de Polignac number, because 20118557 - 2⁴ = 20118541 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 (20118551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12458 + ... + 13979.

It is an arithmetic number, because the mean of its divisors is an integer number (5036439).

Almost surely, 2^20118557 is an apocalyptic number.

It is an amenable number.

20118557 is a deficient number, since it is larger than the sum of its proper divisors (27199).

20118557 is an equidigital number, since it uses as much as digits as its factorization.

20118557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27198.

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 20118557 is about 4485.3714450422. The cubic root of 20118557 is about 271.9770606736.

Adding to 20118557 its reverse (75581102), we get a palindrome (95699659).

The spelling of 20118557 in words is "twenty million, one hundred eighteen thousand, five hundred fifty-seven".