7221999 has 4 divisors (see below), whose sum is σ = 9629336. Its totient is φ = 4814664.

The previous prime is 7221983. The next prime is 7222001. The reversal of 7221999 is 9991227.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9991227 = 3 ⋅3330409.

It is not a de Polignac number, because 7221999 - 2⁴ = 7221983 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 (7221199) 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, 1203664 + ... + 1203669.

It is an arithmetic number, because the mean of its divisors is an integer number (2407334).

Almost surely, 2^7221999 is an apocalyptic number.

7221999 is a deficient number, since it is larger than the sum of its proper divisors (2407337).

7221999 is a wasteful number, since it uses less digits than its factorization.

7221999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2407336.

The product of its digits is 20412, while the sum is 39.

The square root of 7221999 is about 2687.3777181483. The cubic root of 7221999 is about 193.2943417866.

The spelling of 7221999 in words is "seven million, two hundred twenty-one thousand, nine hundred ninety-nine".