1256730221 has 2 divisors, whose sum is σ = 1256730222. Its totient is φ = 1256730220.

The previous prime is 1256730203. The next prime is 1256730263. The reversal of 1256730221 is 1220376521.

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., 1193702500 + 63027721 = 34550^2 + 7939^2 .

It is a cyclic number.

It is not a de Polignac number, because 1256730221 - 2¹⁰ = 1256729197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256739221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628365110 + 628365111.

It is an arithmetic number, because the mean of its divisors is an integer number (628365111).

Almost surely, 2^1256730221 is an apocalyptic number.

It is an amenable number.

1256730221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256730221 is an equidigital number, since it uses as much as digits as its factorization.

1256730221 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 1256730221 is about 35450.3909851499. The cubic root of 1256730221 is about 1079.1471951433.

The spelling of 1256730221 in words is "one billion, two hundred fifty-six million, seven hundred thirty thousand, two hundred twenty-one".