6921816 has 64 divisors (see below), whose sum is σ = 19111680. Its totient is φ = 2071680.

The previous prime is 6921793. The next prime is 6921847. The reversal of 6921816 is 6181296.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is an Ulam number.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41365 + ... + 41531.

It is an arithmetic number, because the mean of its divisors is an integer number (298620).

Almost surely, 2^6921816 is an apocalyptic number.

6921816 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6921816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9555840).

6921816 is an abundant number, since it is smaller than the sum of its proper divisors (12189864).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6921816 is a wasteful number, since it uses less digits than its factorization.

6921816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344 (or 340 counting only the distinct ones).

The product of its digits is 5184, while the sum is 33.

The square root of 6921816 is about 2630.9344347589. The cubic root of 6921816 is about 190.5782567823.

The spelling of 6921816 in words is "six million, nine hundred twenty-one thousand, eight hundred sixteen".