806921 has 4 divisors (see below), whose sum is σ = 826644. Its totient is φ = 787200.

The previous prime is 806917. The next prime is 806929. The reversal of 806921 is 129608.

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

It can be written as a sum of positive squares in 2 ways, for example, as 440896 + 366025 = 664^2 + 605^2 .

It is not a de Polignac number, because 806921 - 2² = 806917 is a prime.

It is a super-2 number, since 2×806921² = 1302243000482, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (806929) 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, 9800 + ... + 9881.

It is an arithmetic number, because the mean of its divisors is an integer number (206661).

2⁸⁰⁶⁹²¹ is an apocalyptic number.

It is an amenable number.

806921 is a deficient number, since it is larger than the sum of its proper divisors (19723).

806921 is a wasteful number, since it uses less digits than its factorization.

806921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19722.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 806921 is about 898.2878157918. The cubic root of 806921 is about 93.0987120070.

The spelling of 806921 in words is "eight hundred six thousand, nine hundred twenty-one".