1631221 has 4 divisors (see below), whose sum is σ = 1687500. Its totient is φ = 1574944.

The previous prime is 1631209. The next prime is 1631243. The reversal of 1631221 is 1221361.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1221361 = 599 ⋅2039.

It can be written as a sum of positive squares in 2 ways, for example, as 1234321 + 396900 = 1111^2 + 630^2 .

It is a cyclic number.

It is not a de Polignac number, because 1631221 - 2¹³ = 1623029 is a prime.

It is a Duffinian number.

1631221 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1631195 and 1631204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1631261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28096 + ... + 28153.

It is an arithmetic number, because the mean of its divisors is an integer number (421875).

2^1631221 is an apocalyptic number.

It is an amenable number.

1631221 is a deficient number, since it is larger than the sum of its proper divisors (56279).

1631221 is an equidigital number, since it uses as much as digits as its factorization.

1631221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56278.

The product of its digits is 72, while the sum is 16.

The square root of 1631221 is about 1277.1926244698. The cubic root of 1631221 is about 117.7165705533.

Adding to 1631221 its reverse (1221361), we get a palindrome (2852582).

The spelling of 1631221 in words is "one million, six hundred thirty-one thousand, two hundred twenty-one".