1240505261 has 2 divisors, whose sum is σ = 1240505262. Its totient is φ = 1240505260.

The previous prime is 1240505243. The next prime is 1240505291. The reversal of 1240505261 is 1625050421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 990675625 + 249829636 = 31475^2 + 15806^2 .

It is an emirp because it is prime and its reverse (1625050421) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1240505261 - 2⁶ = 1240505197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1240505261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1240505291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 620252630 + 620252631.

It is an arithmetic number, because the mean of its divisors is an integer number (620252631).

Almost surely, 2^1240505261 is an apocalyptic number.

It is an amenable number.

1240505261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1240505261 is an equidigital number, since it uses as much as digits as its factorization.

1240505261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 1240505261 is about 35220.8072167575. The cubic root of 1240505261 is about 1074.4829706965.

Adding to 1240505261 its reverse (1625050421), we get a palindrome (2865555682).

The spelling of 1240505261 in words is "one billion, two hundred forty million, five hundred five thousand, two hundred sixty-one".