145521221 has 2 divisors, whose sum is σ = 145521222. Its totient is φ = 145521220.

The previous prime is 145521191. The next prime is 145521227. The reversal of 145521221 is 122125541.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 129640996 + 15880225 = 11386^2 + 3985^2 .

It is a cyclic number.

It is not a de Polignac number, because 145521221 - 2²² = 141326917 is a prime.

It is a super-2 number, since 2×145521221² = 42352851522661682, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (145521227) 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, 72760610 + 72760611.

It is an arithmetic number, because the mean of its divisors is an integer number (72760611).

Almost surely, 2^145521221 is an apocalyptic number.

It is an amenable number.

145521221 is a deficient number, since it is larger than the sum of its proper divisors (1).

145521221 is an equidigital number, since it uses as much as digits as its factorization.

145521221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 800, while the sum is 23.

The square root of 145521221 is about 12063.2176884942. The cubic root of 145521221 is about 525.9875242213.

Adding to 145521221 its reverse (122125541), we get a palindrome (267646762).

The spelling of 145521221 in words is "one hundred forty-five million, five hundred twenty-one thousand, two hundred twenty-one".