1231645 has 4 divisors (see below), whose sum is σ = 1477980. Its totient is φ = 985312.

The previous prime is 1231631. The next prime is 1231663. The reversal of 1231645 is 5461321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5461321 = 193 ⋅28297.

It can be written as a sum of positive squares in 2 ways, for example, as 488601 + 743044 = 699^2 + 862^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231645 - 2⁵ = 1231613 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 123160 + ... + 123169.

It is an arithmetic number, because the mean of its divisors is an integer number (369495).

2^1231645 is an apocalyptic number.

It is an amenable number.

1231645 is a deficient number, since it is larger than the sum of its proper divisors (246335).

1231645 is an equidigital number, since it uses as much as digits as its factorization.

1231645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246334.

The product of its digits is 720, while the sum is 22.

The square root of 1231645 is about 1109.7950261197. The cubic root of 1231645 is about 107.1918704851.

Adding to 1231645 its reverse (5461321), we get a palindrome (6692966).

The spelling of 1231645 in words is "one million, two hundred thirty-one thousand, six hundred forty-five".