819921 has 8 divisors (see below), whose sum is σ = 1097824. Its totient is φ = 544320.

The previous prime is 819913. The next prime is 819937. The reversal of 819921 is 129918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 819921 - 2³ = 819913 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 (819911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 606 + ... + 1416.

It is an arithmetic number, because the mean of its divisors is an integer number (137228).

2⁸¹⁹⁹²¹ is an apocalyptic number.

It is an amenable number.

819921 is a deficient number, since it is larger than the sum of its proper divisors (277903).

819921 is a wasteful number, since it uses less digits than its factorization.

819921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1151.

The product of its digits is 1296, while the sum is 30.

The square root of 819921 is about 905.4948923103. The cubic root of 819921 is about 93.5960103128.

The spelling of 819921 in words is "eight hundred nineteen thousand, nine hundred twenty-one".