1253601721 has 2 divisors, whose sum is σ = 1253601722. Its totient is φ = 1253601720.

The previous prime is 1253601707. The next prime is 1253601737. The reversal of 1253601721 is 1271063521.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1134005625 + 119596096 = 33675^2 + 10936^2 .

It is a cyclic number.

It is not a de Polignac number, because 1253601721 - 2⁵ = 1253601689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1253601721.

It is not a weakly prime, because it can be changed into another prime (1253601751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 626800860 + 626800861.

It is an arithmetic number, because the mean of its divisors is an integer number (626800861).

Almost surely, 2^1253601721 is an apocalyptic number.

It is an amenable number.

1253601721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1253601721 is an equidigital number, since it uses as much as digits as its factorization.

1253601721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 1253601721 is about 35406.2384474827. The cubic root of 1253601721 is about 1078.2509759128.

The spelling of 1253601721 in words is "one billion, two hundred fifty-three million, six hundred one thousand, seven hundred twenty-one".