7217128 has 8 divisors (see below), whose sum is σ = 13532130. Its totient is φ = 3608560.

The previous prime is 7217123. The next prime is 7217137. The reversal of 7217128 is 8217127.

It can be written as a sum of positive squares in only one way, i.e., 4251844 + 2965284 = 2062^2 + 1722^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 7217096 and 7217105.

It is not an unprimeable number, because it can be changed into a prime (7217123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 451063 + ... + 451078.

Almost surely, 2^7217128 is an apocalyptic number.

It is an amenable number.

7217128 is a deficient number, since it is larger than the sum of its proper divisors (6315002).

7217128 is a wasteful number, since it uses less digits than its factorization.

7217128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 902147 (or 902143 counting only the distinct ones).

The product of its digits is 1568, while the sum is 28.

The square root of 7217128 is about 2686.4712914900. The cubic root of 7217128 is about 193.2508751279.

Subtracting 7217128 from its reverse (8217127), we obtain a palindrome (999999).

It can be divided in two parts, 7 and 217128, that multiplied together give a triangular number (1519896 = T₁₇₄₃).

The spelling of 7217128 in words is "seven million, two hundred seventeen thousand, one hundred twenty-eight".