7221428 has 6 divisors (see below), whose sum is σ = 12637506. Its totient is φ = 3610712.

The previous prime is 7221391. The next prime is 7221439. The reversal of 7221428 is 8241227.

It can be written as a sum of positive squares in only one way, i.e., 4571044 + 2650384 = 2138^2 + 1628^2 .

It is a junction number, because it is equal to n+sod(n) for n = 7221397 and 7221406.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 902675 + ... + 902682.

It is an arithmetic number, because the mean of its divisors is an integer number (2106251).

Almost surely, 2^7221428 is an apocalyptic number.

It is an amenable number.

7221428 is a deficient number, since it is larger than the sum of its proper divisors (5416078).

7221428 is a wasteful number, since it uses less digits than its factorization.

7221428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1805361 (or 1805359 counting only the distinct ones).

The product of its digits is 1792, while the sum is 26.

The square root of 7221428 is about 2687.2714786564. The cubic root of 7221428 is about 193.2892474455.

The spelling of 7221428 in words is "seven million, two hundred twenty-one thousand, four hundred twenty-eight".