1521221 has 4 divisors (see below), whose sum is σ = 1638252. Its totient is φ = 1404192.

The previous prime is 1521217. The next prime is 1521227. The reversal of 1521221 is 1221251.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 470596 + 1050625 = 686^2 + 1025^2 .

It is a cyclic number.

It is not a de Polignac number, because 1521221 - 2² = 1521217 is a prime.

It is a super-3 number, since 3×1521221³ = 10560833385765830583, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1521196 and 1521205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1521227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58496 + ... + 58521.

It is an arithmetic number, because the mean of its divisors is an integer number (409563).

2^1521221 is an apocalyptic number.

It is an amenable number.

1521221 is a deficient number, since it is larger than the sum of its proper divisors (117031).

1521221 is a wasteful number, since it uses less digits than its factorization.

1521221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117030.

The product of its digits is 40, while the sum is 14.

The square root of 1521221 is about 1233.3778820783. The cubic root of 1521221 is about 115.0087201957.

Adding to 1521221 its reverse (1221251), we get a palindrome (2742472).

The spelling of 1521221 in words is "one million, five hundred twenty-one thousand, two hundred twenty-one".