1231021009 has 2 divisors, whose sum is σ = 1231021010. Its totient is φ = 1231021008.

The previous prime is 1231020929. The next prime is 1231021013. The reversal of 1231021009 is 9001201321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1226960784 + 4060225 = 35028^2 + 2015^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1231021009 is a prime.

It is not a weakly prime, because it can be changed into another prime (1231021049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615510504 + 615510505.

It is an arithmetic number, because the mean of its divisors is an integer number (615510505).

Almost surely, 2^1231021009 is an apocalyptic number.

It is an amenable number.

1231021009 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231021009 is an equidigital number, since it uses as much as digits as its factorization.

1231021009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 1231021009 is about 35085.9089806720. The cubic root of 1231021009 is about 1071.7376514324.

The spelling of 1231021009 in words is "one billion, two hundred thirty-one million, twenty-one thousand, nine".