7961821 has 4 divisors (see below), whose sum is σ = 9099232. Its totient is φ = 6824412.

The previous prime is 7961809. The next prime is 7961827. The reversal of 7961821 is 1281697.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 7961821 - 2⁷ = 7961693 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 (7961827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 568695 + ... + 568708.

It is an arithmetic number, because the mean of its divisors is an integer number (2274808).

Almost surely, 2^7961821 is an apocalyptic number.

It is an amenable number.

7961821 is a deficient number, since it is larger than the sum of its proper divisors (1137411).

7961821 is a wasteful number, since it uses less digits than its factorization.

7961821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1137410.

The product of its digits is 6048, while the sum is 34.

The square root of 7961821 is about 2821.6698956469. The cubic root of 7961821 is about 199.6813341969.

The spelling of 7961821 in words is "seven million, nine hundred sixty-one thousand, eight hundred twenty-one".