20558557 has 2 divisors, whose sum is σ = 20558558. Its totient is φ = 20558556.

The previous prime is 20558443. The next prime is 20558563. The reversal of 20558557 is 75585502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16818201 + 3740356 = 4101^2 + 1934^2 .

It is a cyclic number.

It is not a de Polignac number, because 20558557 - 2¹⁹ = 20034269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20558567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10279278 + 10279279.

It is an arithmetic number, because the mean of its divisors is an integer number (10279279).

Almost surely, 2^20558557 is an apocalyptic number.

It is an amenable number.

20558557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20558557 is an equidigital number, since it uses as much as digits as its factorization.

20558557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 70000, while the sum is 37.

The square root of 20558557 is about 4534.1544967061. The cubic root of 20558557 is about 273.9455243611.

It can be divided in two parts, 20558 and 557, that added together give a triangular number (21115 = T₂₀₅).

The spelling of 20558557 in words is "twenty million, five hundred fifty-eight thousand, five hundred fifty-seven".