1521224321 has 4 divisors (see below), whose sum is σ = 1526879700. Its totient is φ = 1515568944.

The previous prime is 1521224279. The next prime is 1521224359. The reversal of 1521224321 is 1234221251.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1234221251 = 7253 ⋅170167.

It can be written as a sum of positive squares in 2 ways, for example, as 946423696 + 574800625 = 30764^2 + 23975^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1521224321 is a prime.

It is a super-2 number, since 2×1521224321² = 4628246869603822082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1521224381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2827286 + ... + 2827823.

It is an arithmetic number, because the mean of its divisors is an integer number (381719925).

Almost surely, 2^1521224321 is an apocalyptic number.

It is an amenable number.

1521224321 is a deficient number, since it is larger than the sum of its proper divisors (5655379).

1521224321 is an equidigital number, since it uses as much as digits as its factorization.

1521224321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5655378.

The product of its digits is 960, while the sum is 23.

The square root of 1521224321 is about 39002.8758042276. The cubic root of 1521224321 is about 1150.0880388806.

Adding to 1521224321 its reverse (1234221251), we get a palindrome (2755445572).

The spelling of 1521224321 in words is "one billion, five hundred twenty-one million, two hundred twenty-four thousand, three hundred twenty-one".