1265216398549 has 2 divisors, whose sum is σ = 1265216398550. Its totient is φ = 1265216398548.

The previous prime is 1265216398469. The next prime is 1265216398583. The reversal of 1265216398549 is 9458936125621.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1101723136900 + 163493261649 = 1049630^2 + 404343^2 .

It is a cyclic number.

It is not a de Polignac number, because 1265216398549 - 2²¹ = 1265214301397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1265216398949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 632608199274 + 632608199275.

It is an arithmetic number, because the mean of its divisors is an integer number (632608199275).

Almost surely, 2^{1265216398549} is an apocalyptic number.

It is an amenable number.

1265216398549 is a deficient number, since it is larger than the sum of its proper divisors (1).

1265216398549 is an equidigital number, since it uses as much as digits as its factorization.

1265216398549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27993600, while the sum is 61.

The spelling of 1265216398549 in words is "one trillion, two hundred sixty-five billion, two hundred sixteen million, three hundred ninety-eight thousand, five hundred forty-nine".