816644421 has 12 divisors (see below), whose sum is σ = 1180328448. Its totient is φ = 544092264.

The previous prime is 816644407. The next prime is 816644431. The reversal of 816644421 is 124446618.

It is a happy number.

816644421 is a `hidden beast` number, since 8 + 1 + 6 + 644 + 4 + 2 + 1 = 666.

It is not a de Polignac number, because 816644421 - 2¹⁰ = 816643397 is a prime.

It is a super-2 number, since 2×816644421² = 1333816220700850482, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816644401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12315 + ... + 42248.

It is an arithmetic number, because the mean of its divisors is an integer number (98360704).

Almost surely, 2^816644421 is an apocalyptic number.

It is an amenable number.

816644421 is a deficient number, since it is larger than the sum of its proper divisors (363684027).

816644421 is a wasteful number, since it uses less digits than its factorization.

816644421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56232 (or 56229 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 816644421 is about 28576.9911117318. The cubic root of 816644421 is about 934.7116733251.

The spelling of 816644421 in words is "eight hundred sixteen million, six hundred forty-four thousand, four hundred twenty-one".