20781339 has 4 divisors (see below), whose sum is σ = 27708456. Its totient is φ = 13854224.

The previous prime is 20781337. The next prime is 20781349. The reversal of 20781339 is 93318702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20781339 - 2¹ = 20781337 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20781337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3463554 + ... + 3463559.

It is an arithmetic number, because the mean of its divisors is an integer number (6927114).

Almost surely, 2^20781339 is an apocalyptic number.

20781339 is a deficient number, since it is larger than the sum of its proper divisors (6927117).

20781339 is an equidigital number, since it uses as much as digits as its factorization.

20781339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6927116.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 20781339 is about 4558.6553938634. The cubic root of 20781339 is about 274.9315047041.

The spelling of 20781339 in words is "twenty million, seven hundred eighty-one thousand, three hundred thirty-nine".