1295216721 has 12 divisors (see below), whose sum is σ = 1901539380. Its totient is φ = 849322080.

The previous prime is 1295216707. The next prime is 1295216737. The reversal of 1295216721 is 1276125921.

1295216721 is a `hidden beast` number, since 129 + 521 + 6 + 7 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 450500625 + 844716096 = 21225^2 + 29064^2 .

It is not a de Polignac number, because 1295216721 - 2¹⁰ = 1295215697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1295218721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1179066 + ... + 1180163.

It is an arithmetic number, because the mean of its divisors is an integer number (158461615).

Almost surely, 2^1295216721 is an apocalyptic number.

It is an amenable number.

1295216721 is a deficient number, since it is larger than the sum of its proper divisors (606322659).

1295216721 is a wasteful number, since it uses less digits than its factorization.

1295216721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2359296 (or 2359293 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 1295216721 is about 35989.1194807542. The cubic root of 1295216721 is about 1090.0526644588.

The spelling of 1295216721 in words is "one billion, two hundred ninety-five million, two hundred sixteen thousand, seven hundred twenty-one".