7890221 has 4 divisors (see below), whose sum is σ = 7968444. Its totient is φ = 7812000.

The previous prime is 7890217. The next prime is 7890251. The reversal of 7890221 is 1220987.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6300100 + 1590121 = 2510^2 + 1261^2 .

It is a cyclic number.

It is not a de Polignac number, because 7890221 - 2² = 7890217 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7890251) 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, 38960 + ... + 39161.

It is an arithmetic number, because the mean of its divisors is an integer number (1992111).

Almost surely, 2^7890221 is an apocalyptic number.

It is an amenable number.

7890221 is a deficient number, since it is larger than the sum of its proper divisors (78223).

7890221 is a wasteful number, since it uses less digits than its factorization.

7890221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78222.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 7890221 is about 2808.9537198039. The cubic root of 7890221 is about 199.0809582804.

The spelling of 7890221 in words is "seven million, eight hundred ninety thousand, two hundred twenty-one".