816843021 has 16 divisors (see below), whose sum is σ = 1095621120. Its totient is φ = 541323440.

The previous prime is 816843019. The next prime is 816843031. The reversal of 816843021 is 120348618.

It is a cyclic number.

It is not a de Polignac number, because 816843021 - 2¹ = 816843019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816843031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 519166 + ... + 520736.

It is an arithmetic number, because the mean of its divisors is an integer number (68476320).

Almost surely, 2^816843021 is an apocalyptic number.

It is an amenable number.

816843021 is a deficient number, since it is larger than the sum of its proper divisors (278778099).

816843021 is a wasteful number, since it uses less digits than its factorization.

816843021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2496.

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 816843021 is about 28580.4657239871. The cubic root of 816843021 is about 934.7874381204.

The spelling of 816843021 in words is "eight hundred sixteen million, eight hundred forty-three thousand, twenty-one".