821251 has 4 divisors (see below), whose sum is σ = 849600. Its totient is φ = 792904.

The previous prime is 821209. The next prime is 821263. The reversal of 821251 is 152128.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821281) 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, 14131 + ... + 14188.

It is an arithmetic number, because the mean of its divisors is an integer number (212400).

2⁸²¹²⁵¹ is an apocalyptic number.

821251 is a deficient number, since it is larger than the sum of its proper divisors (28349).

821251 is a wasteful number, since it uses less digits than its factorization.

821251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28348.

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

The square root of 821251 is about 906.2289997567. The cubic root of 821251 is about 93.6465905704.

Adding to 821251 its reverse (152128), we get a palindrome (973379).

The spelling of 821251 in words is "eight hundred twenty-one thousand, two hundred fifty-one".