145131221 has 2 divisors, whose sum is σ = 145131222. Its totient is φ = 145131220.

The previous prime is 145131199. The next prime is 145131247. The reversal of 145131221 is 122131541.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 126112900 + 19018321 = 11230^2 + 4361^2 .

It is a cyclic number.

It is not a de Polignac number, because 145131221 - 2¹⁸ = 144869077 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 145131193 and 145131202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (145131121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 72565610 + 72565611.

It is an arithmetic number, because the mean of its divisors is an integer number (72565611).

Almost surely, 2^145131221 is an apocalyptic number.

It is an amenable number.

145131221 is a deficient number, since it is larger than the sum of its proper divisors (1).

145131221 is an equidigital number, since it uses as much as digits as its factorization.

145131221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 240, while the sum is 20.

The square root of 145131221 is about 12047.0420020850. The cubic root of 145131221 is about 525.5172178704.

Adding to 145131221 its reverse (122131541), we get a palindrome (267262762).

The spelling of 145131221 in words is "one hundred forty-five million, one hundred thirty-one thousand, two hundred twenty-one".