20778 has 8 divisors (see below), whose sum is σ = 41568. Its totient is φ = 6924.

The previous prime is 20773. The next prime is 20789. The reversal of 20778 is 87702.

It is a sphenic number, since it is the product of 3 distinct primes.

20778 is an admirable number.

It is an Ulam number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (20771) 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, 1726 + ... + 1737.

It is an arithmetic number, because the mean of its divisors is an integer number (5196).

2²⁰⁷⁷⁸ is an apocalyptic number.

20778 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20784).

20778 is a wasteful number, since it uses less digits than its factorization.

20778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3468.

The product of its (nonzero) digits is 784, while the sum is 24.

The square root of 20778 is about 144.1457595630. The cubic root of 20778 is about 27.4916779226.

Adding to 20778 its sum of digits (24), we get a palindrome (20802).

The spelling of 20778 in words is "twenty thousand, seven hundred seventy-eight".