7921890 has 96 divisors (see below), whose sum is σ = 22239360. Its totient is φ = 1951488.

The previous prime is 7921889. The next prime is 7921891. The reversal of 7921890 is 981297.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (7921889) and next prime (7921891).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (7921891) 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 47 ways as a sum of consecutive naturals, for example, 88966 + ... + 89054.

It is an arithmetic number, because the mean of its divisors is an integer number (231660).

Almost surely, 2^7921890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7921890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11119680).

7921890 is an abundant number, since it is smaller than the sum of its proper divisors (14317470).

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

7921890 is a wasteful number, since it uses less digits than its factorization.

7921890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168 (or 165 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 7921890 is about 2814.5852269917. The cubic root of 7921890 is about 199.3469533043.

The spelling of 7921890 in words is "seven million, nine hundred twenty-one thousand, eight hundred ninety".