1025821 has 4 divisors (see below), whose sum is σ = 1058944. Its totient is φ = 992700.

The previous prime is 1025819. The next prime is 1025839. The reversal of 1025821 is 1285201.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1285201 = 211 ⋅6091.

It is a cyclic number.

It is not a de Polignac number, because 1025821 - 2¹ = 1025819 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 (1025891) 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, 16515 + ... + 16576.

It is an arithmetic number, because the mean of its divisors is an integer number (264736).

2^1025821 is an apocalyptic number.

It is an amenable number.

1025821 is a deficient number, since it is larger than the sum of its proper divisors (33123).

1025821 is an equidigital number, since it uses as much as digits as its factorization.

1025821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33122.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 1025821 is about 1012.8282184063. The cubic root of 1025821 is about 100.8533964282.

The spelling of 1025821 in words is "one million, twenty-five thousand, eight hundred twenty-one".