20855439439 has 2 divisors, whose sum is σ = 20855439440. Its totient is φ = 20855439438.

The previous prime is 20855439427. The next prime is 20855439533. The reversal of 20855439439 is 93493455802.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20855439439 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20855439419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10427719719 + 10427719720.

It is an arithmetic number, because the mean of its divisors is an integer number (10427719720).

Almost surely, 2^20855439439 is an apocalyptic number.

20855439439 is a deficient number, since it is larger than the sum of its proper divisors (1).

20855439439 is an equidigital number, since it uses as much as digits as its factorization.

20855439439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4665600, while the sum is 52.

The spelling of 20855439439 in words is "twenty billion, eight hundred fifty-five million, four hundred thirty-nine thousand, four hundred thirty-nine".