1521221321 has 2 divisors, whose sum is σ = 1521221322. Its totient is φ = 1521221320.

The previous prime is 1521221291. The next prime is 1521221329. The reversal of 1521221321 is 1231221251.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 928055296 + 593166025 = 30464^2 + 24355^2 .

It is a cyclic number.

It is not a de Polignac number, because 1521221321 - 2⁶ = 1521221257 is a prime.

It is a super-2 number, since 2×1521221321² = 4628228614929970082, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1521221293 and 1521221302.

It is not a weakly prime, because it can be changed into another prime (1521221329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 760610660 + 760610661.

It is an arithmetic number, because the mean of its divisors is an integer number (760610661).

Almost surely, 2^1521221321 is an apocalyptic number.

It is an amenable number.

1521221321 is a deficient number, since it is larger than the sum of its proper divisors (1).

1521221321 is an equidigital number, since it uses as much as digits as its factorization.

1521221321 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 1521221321 is about 39002.8373455060. The cubic root of 1521221321 is about 1150.0872828522.

Adding to 1521221321 its reverse (1231221251), we get a palindrome (2752442572).

The spelling of 1521221321 in words is "one billion, five hundred twenty-one million, two hundred twenty-one thousand, three hundred twenty-one".