821287 has 4 divisors (see below), whose sum is σ = 869616. Its totient is φ = 772960.

The previous prime is 821281. The next prime is 821291. The reversal of 821287 is 782128.

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

It is a cyclic number.

It is not a de Polignac number, because 821287 - 2¹¹ = 819239 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 (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, 24139 + ... + 24172.

It is an arithmetic number, because the mean of its divisors is an integer number (217404).

2⁸²¹²⁸⁷ is an apocalyptic number.

821287 is a deficient number, since it is larger than the sum of its proper divisors (48329).

821287 is a wasteful number, since it uses less digits than its factorization.

821287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48328.

The product of its digits is 1792, while the sum is 28.

The square root of 821287 is about 906.2488620683. The cubic root of 821287 is about 93.6479589008.

It can be divided in two parts, 82 and 1287, that added together give a square (1369 = 37²).

The spelling of 821287 in words is "eight hundred twenty-one thousand, two hundred eighty-seven".