21011222077 has 2 divisors, whose sum is σ = 21011222078. Its totient is φ = 21011222076.

The previous prime is 21011222059. The next prime is 21011222081. The reversal of 21011222077 is 77022211012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11220317476 + 9790904601 = 105926^2 + 98949^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21011222077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011222047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505611038 + 10505611039.

It is an arithmetic number, because the mean of its divisors is an integer number (10505611039).

Almost surely, 2^21011222077 is an apocalyptic number.

It is an amenable number.

21011222077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011222077 is an equidigital number, since it uses as much as digits as its factorization.

21011222077 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 784, while the sum is 25.

Adding to 21011222077 its reverse (77022211012), we get a palindrome (98033433089).

The spelling of 21011222077 in words is "twenty-one billion, eleven million, two hundred twenty-two thousand, seventy-seven".