1821965 has 4 divisors (see below), whose sum is σ = 2186364. Its totient is φ = 1457568.

The previous prime is 1821959. The next prime is 1821997. The reversal of 1821965 is 5691281.

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 1387684 + 434281 = 1178^2 + 659^2 .

It is a cyclic number.

It is not a de Polignac number, because 1821965 - 2⁸ = 1821709 is a prime.

It is a super-2 number, since 2×1821965² = 6639112922450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 182192 + ... + 182201.

It is an arithmetic number, because the mean of its divisors is an integer number (546591).

2^1821965 is an apocalyptic number.

It is an amenable number.

1821965 is a deficient number, since it is larger than the sum of its proper divisors (364399).

1821965 is an equidigital number, since it uses as much as digits as its factorization.

1821965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364398.

The product of its digits is 4320, while the sum is 32.

The square root of 1821965 is about 1349.8018373080. The cubic root of 1821965 is about 122.1368392032.

The spelling of 1821965 in words is "one million, eight hundred twenty-one thousand, nine hundred sixty-five".