1261258261 has 2 divisors, whose sum is σ = 1261258262. Its totient is φ = 1261258260.

The previous prime is 1261258217. The next prime is 1261258267. The reversal of 1261258261 is 1628521621.

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., 1096007236 + 165251025 = 33106^2 + 12855^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261258261 - 2¹⁹ = 1260733973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1261258267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630629130 + 630629131.

It is an arithmetic number, because the mean of its divisors is an integer number (630629131).

Almost surely, 2^1261258261 is an apocalyptic number.

It is an amenable number.

1261258261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261258261 is an equidigital number, since it uses as much as digits as its factorization.

1261258261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 34.

The square root of 1261258261 is about 35514.1980199469. The cubic root of 1261258261 is about 1080.4417091813.

Adding to 1261258261 its reverse (1628521621), we get a palindrome (2889779882).

The spelling of 1261258261 in words is "one billion, two hundred sixty-one million, two hundred fifty-eight thousand, two hundred sixty-one".