20550557 has 4 divisors (see below), whose sum is σ = 20628960. Its totient is φ = 20472156.

The previous prime is 20550547. The next prime is 20550587. The reversal of 20550557 is 75505502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20550557 - 2⁶ = 20550493 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 (20550547) 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, 38807 + ... + 39332.

It is an arithmetic number, because the mean of its divisors is an integer number (5157240).

Almost surely, 2^20550557 is an apocalyptic number.

It is an amenable number.

20550557 is a deficient number, since it is larger than the sum of its proper divisors (78403).

20550557 is an equidigital number, since it uses as much as digits as its factorization.

20550557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78402.

The product of its (nonzero) digits is 8750, while the sum is 29.

The square root of 20550557 is about 4533.2722177253. The cubic root of 20550557 is about 273.9099860606.

The spelling of 20550557 in words is "twenty million, five hundred fifty thousand, five hundred fifty-seven".