1356821 has 4 divisors (see below), whose sum is σ = 1436652. Its totient is φ = 1276992.

The previous prime is 1356811. The next prime is 1356829. The reversal of 1356821 is 1286531.

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 1234321 + 122500 = 1111^2 + 350^2 .

It is a cyclic number.

It is not a de Polignac number, because 1356821 - 2⁶ = 1356757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1356829) 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, 39890 + ... + 39923.

It is an arithmetic number, because the mean of its divisors is an integer number (359163).

2^1356821 is an apocalyptic number.

It is an amenable number.

1356821 is a deficient number, since it is larger than the sum of its proper divisors (79831).

1356821 is an equidigital number, since it uses as much as digits as its factorization.

1356821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79830.

The product of its digits is 1440, while the sum is 26.

The square root of 1356821 is about 1164.8265965370. The cubic root of 1356821 is about 110.7067714438.

The spelling of 1356821 in words is "one million, three hundred fifty-six thousand, eight hundred twenty-one".