1561221 has 16 divisors (see below), whose sum is σ = 2358720. Its totient is φ = 1020240.

The previous prime is 1561213. The next prime is 1561243. The reversal of 1561221 is 1221651.

It is not a de Polignac number, because 1561221 - 2³ = 1561213 is a prime.

It is a super-2 number, since 2×1561221² = 4874822021682, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1561194 and 1561203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561121) 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 15 ways as a sum of consecutive naturals, for example, 886 + ... + 1976.

It is an arithmetic number, because the mean of its divisors is an integer number (147420).

2^1561221 is an apocalyptic number.

It is an amenable number.

1561221 is a deficient number, since it is larger than the sum of its proper divisors (797499).

1561221 is a wasteful number, since it uses less digits than its factorization.

1561221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1153 (or 1147 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 1561221 is about 1249.4882952633. The cubic root of 1561221 is about 116.0080503727.

Adding to 1561221 its reverse (1221651), we get a palindrome (2782872).

The spelling of 1561221 in words is "one million, five hundred sixty-one thousand, two hundred twenty-one".