1265349721 has 8 divisors (see below), whose sum is σ = 1309699080. Its totient is φ = 1221048192.

The previous prime is 1265349713. The next prime is 1265349733. The reversal of 1265349721 is 1279435621.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 473715225 + 791634496 = 21765^2 + 28136^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1265349721 - 2³ = 1265349713 is a prime.

It is a super-2 number, since 2×1265349721² = 3202219832869555682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1265349781) 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 in 7 ways as a sum of consecutive naturals, for example, 46851 + ... + 68743.

It is an arithmetic number, because the mean of its divisors is an integer number (163712385).

Almost surely, 2^1265349721 is an apocalyptic number.

It is an amenable number.

1265349721 is a deficient number, since it is larger than the sum of its proper divisors (44349359).

1265349721 is a wasteful number, since it uses less digits than its factorization.

1265349721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23915.

The product of its digits is 90720, while the sum is 40.

The square root of 1265349721 is about 35571.7545392408. The cubic root of 1265349721 is about 1081.6087481389.

The spelling of 1265349721 in words is "one billion, two hundred sixty-five million, three hundred forty-nine thousand, seven hundred twenty-one".