1231621 has 4 divisors (see below), whose sum is σ = 1235500. Its totient is φ = 1227744.

The previous prime is 1231613. The next prime is 1231631. The reversal of 1231621 is 1261321.

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 474721 + 756900 = 689^2 + 870^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231621 - 2³ = 1231613 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1231595 and 1231604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231631) 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, 1416 + ... + 2113.

It is an arithmetic number, because the mean of its divisors is an integer number (308875).

2^1231621 is an apocalyptic number.

It is an amenable number.

1231621 is a deficient number, since it is larger than the sum of its proper divisors (3879).

1231621 is an equidigital number, since it uses as much as digits as its factorization.

1231621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3878.

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

The square root of 1231621 is about 1109.7842132595. The cubic root of 1231621 is about 107.1911742288.

Adding to 1231621 its reverse (1261321), we get a palindrome (2492942).

The spelling of 1231621 in words is "one million, two hundred thirty-one thousand, six hundred twenty-one".