1821521 has 8 divisors (see below), whose sum is σ = 1994664. Its totient is φ = 1653120.

The previous prime is 1821509. The next prime is 1821541. The reversal of 1821521 is 1251281.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 25921 + 1795600 = 161^2 + 1340^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1821521 - 2¹⁴ = 1805137 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1821493 and 1821502.

It is not an unprimeable number, because it can be changed into a prime (1821541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 356 + ... + 1941.

It is an arithmetic number, because the mean of its divisors is an integer number (249333).

2^1821521 is an apocalyptic number.

It is an amenable number.

1821521 is a deficient number, since it is larger than the sum of its proper divisors (173143).

1821521 is a wasteful number, since it uses less digits than its factorization.

1821521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2371.

The product of its digits is 160, while the sum is 20.

The square root of 1821521 is about 1349.6373587005. The cubic root of 1821521 is about 122.1269171022.

The spelling of 1821521 in words is "one million, eight hundred twenty-one thousand, five hundred twenty-one".