1221521 has 12 divisors (see below), whose sum is σ = 1441188. Its totient is φ = 1032192.

The previous prime is 1221503. The next prime is 1221523. The reversal of 1221521 is 1251221.

It can be written as a sum of positive squares in 2 ways, for example, as 960400 + 261121 = 980^2 + 511^2 .

It is not a de Polignac number, because 1221521 - 2⁶ = 1221457 is a prime.

It is a super-2 number, since 2×1221521² = 2984227106882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221496 and 1221505.

It is not an unprimeable number, because it can be changed into a prime (1221523) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4625 + ... + 4881.

It is an arithmetic number, because the mean of its divisors is an integer number (120099).

2^1221521 is an apocalyptic number.

It is an amenable number.

1221521 is a deficient number, since it is larger than the sum of its proper divisors (219667).

1221521 is an equidigital number, since it uses as much as digits as its factorization.

1221521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368 (or 361 counting only the distinct ones).

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

The square root of 1221521 is about 1105.2244116016. The cubic root of 1221521 is about 106.8973598669.

Adding to 1221521 its reverse (1251221), we get a palindrome (2472742).

The spelling of 1221521 in words is "one million, two hundred twenty-one thousand, five hundred twenty-one".