1255021561 has 2 divisors, whose sum is σ = 1255021562. Its totient is φ = 1255021560.

The previous prime is 1255021451. The next prime is 1255021567. The reversal of 1255021561 is 1651205521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 819047161 + 435974400 = 28619^2 + 20880^2 .

It is a cyclic number.

It is not a de Polignac number, because 1255021561 - 2⁷ = 1255021433 is a prime.

It is a super-3 number, since 3×1255021561³ (a number of 28 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1255021567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 627510780 + 627510781.

It is an arithmetic number, because the mean of its divisors is an integer number (627510781).

Almost surely, 2^1255021561 is an apocalyptic number.

It is an amenable number.

1255021561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1255021561 is an equidigital number, since it uses as much as digits as its factorization.

1255021561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3000, while the sum is 28.

The square root of 1255021561 is about 35426.2834771021. The cubic root of 1255021561 is about 1078.6579010727.

The spelling of 1255021561 in words is "one billion, two hundred fifty-five million, twenty-one thousand, five hundred sixty-one".