817823421 has 6 divisors (see below), whose sum is σ = 1181300510. Its totient is φ = 545215608.

The previous prime is 817823389. The next prime is 817823423. The reversal of 817823421 is 124328718.

It can be written as a sum of positive squares in only one way, i.e., 814474521 + 3348900 = 28539^2 + 1830^2 .

It is not a de Polignac number, because 817823421 - 2⁵ = 817823389 is a prime.

It is a super-2 number, since 2×817823421² = 1337670295872286482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (817823423) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 45434626 + ... + 45434643.

Almost surely, 2^817823421 is an apocalyptic number.

It is an amenable number.

817823421 is a deficient number, since it is larger than the sum of its proper divisors (363477089).

817823421 is a wasteful number, since it uses less digits than its factorization.

817823421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90869275 (or 90869272 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 817823421 is about 28597.6121555629. The cubic root of 817823421 is about 935.1612754300.

The spelling of 817823421 in words is "eight hundred seventeen million, eight hundred twenty-three thousand, four hundred twenty-one".