7971821 has 16 divisors (see below), whose sum is σ = 9471168. Its totient is φ = 6614400.

The previous prime is 7971787. The next prime is 7971833. The reversal of 7971821 is 1281797.

It is not a de Polignac number, because 7971821 - 2⁶ = 7971757 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 (7971851) 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, 15041 + ... + 15561.

It is an arithmetic number, because the mean of its divisors is an integer number (591948).

Almost surely, 2^7971821 is an apocalyptic number.

It is an amenable number.

7971821 is a deficient number, since it is larger than the sum of its proper divisors (1499347).

7971821 is a wasteful number, since it uses less digits than its factorization.

7971821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 652.

The product of its digits is 7056, while the sum is 35.

The square root of 7971821 is about 2823.4413399254. The cubic root of 7971821 is about 199.7648987453.

The spelling of 7971821 in words is "seven million, nine hundred seventy-one thousand, eight hundred twenty-one".