1256032721 has 2 divisors, whose sum is σ = 1256032722. Its totient is φ = 1256032720.

The previous prime is 1256032681. The next prime is 1256032733. The reversal of 1256032721 is 1272306521.

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., 1109622721 + 146410000 = 33311^2 + 12100^2 .

It is a cyclic number.

It is not a de Polignac number, because 1256032721 - 2¹⁰ = 1256031697 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1256032741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628016360 + 628016361.

It is an arithmetic number, because the mean of its divisors is an integer number (628016361).

Almost surely, 2^1256032721 is an apocalyptic number.

It is an amenable number.

1256032721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256032721 is an equidigital number, since it uses as much as digits as its factorization.

1256032721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 1256032721 is about 35440.5519285465. The cubic root of 1256032721 is about 1078.9475117500.

The spelling of 1256032721 in words is "one billion, two hundred fifty-six million, thirty-two thousand, seven hundred twenty-one".