258821 has 4 divisors (see below), whose sum is σ = 262752. Its totient is φ = 254892.

The previous prime is 258809. The next prime is 258827. The reversal of 258821 is 128852.

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.

It is a cyclic number.

It is not a de Polignac number, because 258821 - 2¹⁰ = 257797 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 (258827) 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, 1865 + ... + 1998.

It is an arithmetic number, because the mean of its divisors is an integer number (65688).

2²⁵⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

258821 is a deficient number, since it is larger than the sum of its proper divisors (3931).

258821 is an equidigital number, since it uses as much as digits as its factorization.

258821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3930.

The product of its digits is 1280, while the sum is 26.

The square root of 258821 is about 508.7445331402. The cubic root of 258821 is about 63.7284227887.

The spelling of 258821 in words is "two hundred fifty-eight thousand, eight hundred twenty-one".