1215395240261 has 2 divisors, whose sum is σ = 1215395240262. Its totient is φ = 1215395240260.

The previous prime is 1215395240239. The next prime is 1215395240299. The reversal of 1215395240261 is 1620425935121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1211938976161 + 3456264100 = 1100881^2 + 58790^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1215395240261 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1215395240231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607697620130 + 607697620131.

It is an arithmetic number, because the mean of its divisors is an integer number (607697620131).

Almost surely, 2^{1215395240261} is an apocalyptic number.

It is an amenable number.

1215395240261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215395240261 is an equidigital number, since it uses as much as digits as its factorization.

1215395240261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 129600, while the sum is 41.

The spelling of 1215395240261 in words is "one trillion, two hundred fifteen billion, three hundred ninety-five million, two hundred forty thousand, two hundred sixty-one".