21011042140261 has 2 divisors, whose sum is σ = 21011042140262. Its totient is φ = 21011042140260.

The previous prime is 21011042140247. The next prime is 21011042140351. The reversal of 21011042140261 is 16204124011012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16033569589636 + 4977472550625 = 4004194^2 + 2231025^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011042140261 - 2¹⁷ = 21011042009189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011042141261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505521070130 + 10505521070131.

It is an arithmetic number, because the mean of its divisors is an integer number (10505521070131).

Almost surely, 2^{21011042140261} is an apocalyptic number.

It is an amenable number.

21011042140261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011042140261 is an equidigital number, since it uses as much as digits as its factorization.

21011042140261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 768, while the sum is 25.

Adding to 21011042140261 its reverse (16204124011012), we get a palindrome (37215166151273).

The spelling of 21011042140261 in words is "twenty-one trillion, eleven billion, forty-two million, one hundred forty thousand, two hundred sixty-one".