1213621 has 4 divisors (see below), whose sum is σ = 1255500. Its totient is φ = 1171744.

The previous prime is 1213607. The next prime is 1213627. The reversal of 1213621 is 1263121.

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 835396 + 378225 = 914^2 + 615^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213621 - 2⁹ = 1213109 is a prime.

It is a Duffinian number.

1213621 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1213595 and 1213604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213627) 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, 20896 + ... + 20953.

It is an arithmetic number, because the mean of its divisors is an integer number (313875).

2^1213621 is an apocalyptic number.

It is an amenable number.

1213621 is a deficient number, since it is larger than the sum of its proper divisors (41879).

1213621 is an equidigital number, since it uses as much as digits as its factorization.

1213621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41878.

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

The square root of 1213621 is about 1101.6446795587. The cubic root of 1213621 is about 106.6664138449. Note that the first 3 decimals are identical.

Adding to 1213621 its reverse (1263121), we get a palindrome (2476742).

The spelling of 1213621 in words is "one million, two hundred thirteen thousand, six hundred twenty-one".