20889771779 has 2 divisors, whose sum is σ = 20889771780. Its totient is φ = 20889771778.

The previous prime is 20889771739. The next prime is 20889771823. The reversal of 20889771779 is 97717798802.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20889771779 is a prime.

It is not a weakly prime, because it can be changed into another prime (20889771739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10444885889 + 10444885890.

It is an arithmetic number, because the mean of its divisors is an integer number (10444885890).

Almost surely, 2^20889771779 is an apocalyptic number.

20889771779 is a deficient number, since it is larger than the sum of its proper divisors (1).

20889771779 is an equidigital number, since it uses as much as digits as its factorization.

20889771779 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24893568, while the sum is 65.

The spelling of 20889771779 in words is "twenty billion, eight hundred eighty-nine million, seven hundred seventy-one thousand, seven hundred seventy-nine".