1813621 has 4 divisors (see below), whose sum is σ = 1823212. Its totient is φ = 1804032.

The previous prime is 1813613. The next prime is 1813627. The reversal of 1813621 is 1263181.

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 152100 + 1661521 = 390^2 + 1289^2 .

It is a cyclic number.

It is not a de Polignac number, because 1813621 - 2³ = 1813613 is a prime.

It is a super-2 number, since 2×1813621² = 6578442263282, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1813592 and 1813601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1813627) 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, 4506 + ... + 4891.

It is an arithmetic number, because the mean of its divisors is an integer number (455803).

2^1813621 is an apocalyptic number.

It is an amenable number.

1813621 is a deficient number, since it is larger than the sum of its proper divisors (9591).

1813621 is an equidigital number, since it uses as much as digits as its factorization.

1813621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9590.

The product of its digits is 288, while the sum is 22.

The square root of 1813621 is about 1346.7074663786. The cubic root of 1813621 is about 121.9501050113.

The spelling of 1813621 in words is "one million, eight hundred thirteen thousand, six hundred twenty-one".