1265021261 has 4 divisors (see below), whose sum is σ = 1445738592. Its totient is φ = 1084303932.

The previous prime is 1265021249. The next prime is 1265021293. The reversal of 1265021261 is 1621205621.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1265021261 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1265021261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1265020261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90358655 + ... + 90358668.

It is an arithmetic number, because the mean of its divisors is an integer number (361434648).

Almost surely, 2^1265021261 is an apocalyptic number.

It is an amenable number.

1265021261 is a deficient number, since it is larger than the sum of its proper divisors (180717331).

1265021261 is an equidigital number, since it uses as much as digits as its factorization.

1265021261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180717330.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 1265021261 is about 35567.1373742673. The cubic root of 1265021261 is about 1081.5151518923.

Adding to 1265021261 its reverse (1621205621), we get a palindrome (2886226882).

The spelling of 1265021261 in words is "one billion, two hundred sixty-five million, twenty-one thousand, two hundred sixty-one".