1231211161 has 2 divisors, whose sum is σ = 1231211162. Its totient is φ = 1231211160.

The previous prime is 1231211123. The next prime is 1231211171. The reversal of 1231211161 is 1611121321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1032401161 + 198810000 = 32131^2 + 14100^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231211161 - 2⁹ = 1231210649 is a prime.

It is a super-3 number, since 3×1231211161³ (a number of 28 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1231211171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615605580 + 615605581.

It is an arithmetic number, because the mean of its divisors is an integer number (615605581).

Almost surely, 2^1231211161 is an apocalyptic number.

It is an amenable number.

1231211161 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231211161 is an equidigital number, since it uses as much as digits as its factorization.

1231211161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 19.

The square root of 1231211161 is about 35088.6186818461. The cubic root of 1231211161 is about 1071.7928312558.

Adding to 1231211161 its reverse (1611121321), we get a palindrome (2842332482).

The spelling of 1231211161 in words is "one billion, two hundred thirty-one million, two hundred eleven thousand, one hundred sixty-one".