20805057 has 72 divisors (see below), whose sum is σ = 39836160. Its totient is φ = 10342080.

The previous prime is 20805049. The next prime is 20805089. The reversal of 20805057 is 75050802.

It is a happy number.

It is not a de Polignac number, because 20805057 - 2³ = 20805049 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20805057.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20805017) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 108832 + ... + 109022.

It is an arithmetic number, because the mean of its divisors is an integer number (553280).

Almost surely, 2^20805057 is an apocalyptic number.

It is an amenable number.

20805057 is a deficient number, since it is larger than the sum of its proper divisors (19031103).

20805057 is a wasteful number, since it uses less digits than its factorization.

20805057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243 (or 233 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 27.

The square root of 20805057 is about 4561.2560770034. The cubic root of 20805057 is about 275.0360591834.

Adding to 20805057 its reverse (75050802), we get a palindrome (95855859).

The spelling of 20805057 in words is "twenty million, eight hundred five thousand, fifty-seven".