1213221521 has 2 divisors, whose sum is σ = 1213221522. Its totient is φ = 1213221520.

The previous prime is 1213221511. The next prime is 1213221539. The reversal of 1213221521 is 1251223121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1212780625 + 440896 = 34825^2 + 664^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213221521 - 2¹⁰ = 1213220497 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1213221493 and 1213221502.

It is not a weakly prime, because it can be changed into another prime (1213221511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606610760 + 606610761.

It is an arithmetic number, because the mean of its divisors is an integer number (606610761).

Almost surely, 2^1213221521 is an apocalyptic number.

It is an amenable number.

1213221521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213221521 is an equidigital number, since it uses as much as digits as its factorization.

1213221521 is an evil number, because the sum of its binary digits is even.

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

The square root of 1213221521 is about 34831.3295898965. The cubic root of 1213221521 is about 1066.5470901872.

Adding to 1213221521 its reverse (1251223121), we get a palindrome (2464444642).

The spelling of 1213221521 in words is "one billion, two hundred thirteen million, two hundred twenty-one thousand, five hundred twenty-one".