20288557 has 2 divisors, whose sum is σ = 20288558. Its totient is φ = 20288556.

The previous prime is 20288533. The next prime is 20288621. The reversal of 20288557 is 75588202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12257001 + 8031556 = 3501^2 + 2834^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20288557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20288657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10144278 + 10144279.

It is an arithmetic number, because the mean of its divisors is an integer number (10144279).

Almost surely, 2^20288557 is an apocalyptic number.

It is an amenable number.

20288557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20288557 is an equidigital number, since it uses as much as digits as its factorization.

20288557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 44800, while the sum is 37.

The square root of 20288557 is about 4504.2820737605. The cubic root of 20288557 is about 272.7409736114.

It can be divided in two parts, 2028 and 8557, that added together give a triangular number (10585 = T₁₄₅).

The spelling of 20288557 in words is "twenty million, two hundred eighty-eight thousand, five hundred fifty-seven".