135221521 has 2 divisors, whose sum is σ = 135221522. Its totient is φ = 135221520.

The previous prime is 135221503. The next prime is 135221533. The reversal of 135221521 is 125122531.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 99221521 + 36000000 = 9961^2 + 6000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-135221521 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 135221492 and 135221501.

It is not a weakly prime, because it can be changed into another prime (135221501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 67610760 + 67610761.

It is an arithmetic number, because the mean of its divisors is an integer number (67610761).

Almost surely, 2^135221521 is an apocalyptic number.

It is an amenable number.

135221521 is a deficient number, since it is larger than the sum of its proper divisors (1).

135221521 is an equidigital number, since it uses as much as digits as its factorization.

135221521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 600, while the sum is 22.

The square root of 135221521 is about 11628.4788773081. The cubic root of 135221521 is about 513.2732199899.

The spelling of 135221521 in words is "one hundred thirty-five million, two hundred twenty-one thousand, five hundred twenty-one".