7217512021 has 4 divisors (see below), whose sum is σ = 7218932044. Its totient is φ = 7216092000.

The previous prime is 7217512019. The next prime is 7217512111. The reversal of 7217512021 is 1202157127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1202157127 = 311 ⋅3865457.

It can be written as a sum of positive squares in 2 ways, for example, as 2219728996 + 4997783025 = 47114^2 + 70695^2 .

It is a cyclic number.

It is not a de Polignac number, because 7217512021 - 2¹ = 7217512019 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 (7217513021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 702360 + ... + 712561.

It is an arithmetic number, because the mean of its divisors is an integer number (1804733011).

Almost surely, 2^7217512021 is an apocalyptic number.

It is an amenable number.

7217512021 is a deficient number, since it is larger than the sum of its proper divisors (1420023).

7217512021 is a wasteful number, since it uses less digits than its factorization.

7217512021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1420022.

The product of its (nonzero) digits is 1960, while the sum is 28.

The square root of 7217512021 is about 84955.9416462439. The cubic root of 7217512021 is about 1932.5430267221.

Adding to 7217512021 its reverse (1202157127), we get a palindrome (8419669148).

The spelling of 7217512021 in words is "seven billion, two hundred seventeen million, five hundred twelve thousand, twenty-one".