20778143 has 4 divisors (see below), whose sum is σ = 20851848. Its totient is φ = 20704440.

The previous prime is 20778139. The next prime is 20778151. The reversal of 20778143 is 34187702.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34187702 = 2 ⋅17093851.

It is a cyclic number.

It is not a de Polignac number, because 20778143 - 2² = 20778139 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 (20778113) 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, 36428 + ... + 36993.

It is an arithmetic number, because the mean of its divisors is an integer number (5212962).

Almost surely, 2^20778143 is an apocalyptic number.

20778143 is a deficient number, since it is larger than the sum of its proper divisors (73705).

20778143 is an equidigital number, since it uses as much as digits as its factorization.

20778143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73704.

The product of its (nonzero) digits is 9408, while the sum is 32.

The square root of 20778143 is about 4558.3048384240. The cubic root of 20778143 is about 274.9174099091.

The spelling of 20778143 in words is "twenty million, seven hundred seventy-eight thousand, one hundred forty-three".