1213645 has 4 divisors (see below), whose sum is σ = 1456380. Its totient is φ = 970912.

The previous prime is 1213643. The next prime is 1213651. The reversal of 1213645 is 5463121.

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 477481 + 736164 = 691^2 + 858^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213645 - 2¹ = 1213643 is a prime.

It is a super-3 number, since 3×1213645³ = 5362857630594933375, which contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213643) 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, 121360 + ... + 121369.

It is an arithmetic number, because the mean of its divisors is an integer number (364095).

2^1213645 is an apocalyptic number.

It is an amenable number.

1213645 is a deficient number, since it is larger than the sum of its proper divisors (242735).

1213645 is an equidigital number, since it uses as much as digits as its factorization.

1213645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242734.

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

The square root of 1213645 is about 1101.6555723092. The cubic root of 1213645 is about 106.6671169686.

Adding to 1213645 its reverse (5463121), we get a palindrome (6676766).

The spelling of 1213645 in words is "one million, two hundred thirteen thousand, six hundred forty-five".