1231226561 has 2 divisors, whose sum is σ = 1231226562. Its totient is φ = 1231226560.

The previous prime is 1231226537. The next prime is 1231226603. The reversal of 1231226561 is 1656221321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 831226561 + 400000000 = 28831^2 + 20000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1231226561 is a prime.

It is a super-3 number, since 3×1231226561³ (a number of 28 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1231226861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615613280 + 615613281.

It is an arithmetic number, because the mean of its divisors is an integer number (615613281).

Almost surely, 2^1231226561 is an apocalyptic number.

It is an amenable number.

1231226561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231226561 is an equidigital number, since it uses as much as digits as its factorization.

1231226561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 29.

The square root of 1231226561 is about 35088.8381255350. The cubic root of 1231226561 is about 1071.7972999019.

Adding to 1231226561 its reverse (1656221321), we get a palindrome (2887447882).

The spelling of 1231226561 in words is "one billion, two hundred thirty-one million, two hundred twenty-six thousand, five hundred sixty-one".