20979221111 has 2 divisors, whose sum is σ = 20979221112. Its totient is φ = 20979221110.

The previous prime is 20979221071. The next prime is 20979221117. The reversal of 20979221111 is 11112297902.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20979221111 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20979221117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10489610555 + 10489610556.

It is an arithmetic number, because the mean of its divisors is an integer number (10489610556).

Almost surely, 2^20979221111 is an apocalyptic number.

20979221111 is a deficient number, since it is larger than the sum of its proper divisors (1).

20979221111 is an equidigital number, since it uses as much as digits as its factorization.

20979221111 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 35.

The spelling of 20979221111 in words is "twenty billion, nine hundred seventy-nine million, two hundred twenty-one thousand, one hundred eleven".