1231166021 has 2 divisors, whose sum is σ = 1231166022. Its totient is φ = 1231166020.

The previous prime is 1231166003. The next prime is 1231166033. The reversal of 1231166021 is 1206611321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 643636900 + 587529121 = 25370^2 + 24239^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231166021 - 2¹⁰ = 1231164997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231106021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615583010 + 615583011.

It is an arithmetic number, because the mean of its divisors is an integer number (615583011).

Almost surely, 2^1231166021 is an apocalyptic number.

It is an amenable number.

1231166021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231166021 is an equidigital number, since it uses as much as digits as its factorization.

1231166021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 1231166021 is about 35087.9754474378. The cubic root of 1231166021 is about 1071.7797326850.

Adding to 1231166021 its reverse (1206611321), we get a palindrome (2437777342).

The spelling of 1231166021 in words is "one billion, two hundred thirty-one million, one hundred sixty-six thousand, twenty-one".