890821 has 2 divisors, whose sum is σ = 890822. Its totient is φ = 890820.

The previous prime is 890809. The next prime is 890833. The reversal of 890821 is 128098.

It is a balanced prime because it is at equal distance from previous prime (890809) and next prime (890833).

It can be written as a sum of positive squares in only one way, i.e., 864900 + 25921 = 930^2 + 161^2 .

It is a cyclic number.

It is not a de Polignac number, because 890821 - 2⁵ = 890789 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 890821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (890861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445410 + 445411.

It is an arithmetic number, because the mean of its divisors is an integer number (445411).

2⁸⁹⁰⁸²¹ is an apocalyptic number.

890821 is the 505-th centered heptagonal number.

It is an amenable number.

890821 is a deficient number, since it is larger than the sum of its proper divisors (1).

890821 is an equidigital number, since it uses as much as digits as its factorization.

890821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 890821 is about 943.8331420331. The cubic root of 890821 is about 96.2195856002.

It can be divided in two parts, 890 and 821, that added together give a triangular number (1711 = T₅₈).

The spelling of 890821 in words is "eight hundred ninety thousand, eight hundred twenty-one".