21011044777777 has 2 divisors, whose sum is σ = 21011044777778. Its totient is φ = 21011044777776.

The previous prime is 21011044777741. The next prime is 21011044777841. The reversal of 21011044777777 is 77777744011012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17663897688336 + 3347147089441 = 4202844^2 + 1829521^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21011044777777 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011048777777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505522388888 + 10505522388889.

It is an arithmetic number, because the mean of its divisors is an integer number (10505522388889).

Almost surely, 2^{21011044777777} is an apocalyptic number.

It is an amenable number.

21011044777777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011044777777 is an equidigital number, since it uses as much as digits as its factorization.

21011044777777 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3764768, while the sum is 55.

Adding to 21011044777777 its reverse (77777744011012), we get a palindrome (98788788788789).

The spelling of 21011044777777 in words is "twenty-one trillion, eleven billion, forty-four million, seven hundred seventy-seven thousand, seven hundred seventy-seven".