821573 has 2 divisors, whose sum is σ = 821574. Its totient is φ = 821572.

The previous prime is 821551. The next prime is 821603. The reversal of 821573 is 375128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 574564 + 247009 = 758^2 + 497^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821573 is a prime.

It is a plaindrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410786 + 410787.

It is an arithmetic number, because the mean of its divisors is an integer number (410787).

2⁸²¹⁵⁷³ is an apocalyptic number.

It is an amenable number.

821573 is a deficient number, since it is larger than the sum of its proper divisors (1).

821573 is an equidigital number, since it uses as much as digits as its factorization.

821573 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 26.

The square root of 821573 is about 906.4066416350. The cubic root of 821573 is about 93.6588281048.

The spelling of 821573 in words is "eight hundred twenty-one thousand, five hundred seventy-three".