20255781 has 16 divisors (see below), whose sum is σ = 33240704. Its totient is φ = 10684224.

The previous prime is 20255773. The next prime is 20255783. The reversal of 20255781 is 18755202.

It is not a de Polignac number, because 20255781 - 2³ = 20255773 is a prime.

It is a super-2 number, since 2×20255781² = 820593327839922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20255783) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36826 + ... + 37371.

It is an arithmetic number, because the mean of its divisors is an integer number (2077544).

Almost surely, 2^20255781 is an apocalyptic number.

20255781 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20255781 is a deficient number, since it is larger than the sum of its proper divisors (12984923).

20255781 is a wasteful number, since it uses less digits than its factorization.

20255781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74220.

The product of its (nonzero) digits is 5600, while the sum is 30.

The square root of 20255781 is about 4500.6422874963. The cubic root of 20255781 is about 272.5940241709.

The spelling of 20255781 in words is "twenty million, two hundred fifty-five thousand, seven hundred eighty-one".