7521061721 has 2 divisors, whose sum is σ = 7521061722. Its totient is φ = 7521061720.

The previous prime is 7521061703. The next prime is 7521061747. The reversal of 7521061721 is 1271601257.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5047392025 + 2473669696 = 71045^2 + 49736^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7521061721 is a prime.

It is a super-2 number, since 2×7521061721² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (7521061421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3760530860 + 3760530861.

It is an arithmetic number, because the mean of its divisors is an integer number (3760530861).

Almost surely, 2^7521061721 is an apocalyptic number.

It is an amenable number.

7521061721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7521061721 is an equidigital number, since it uses as much as digits as its factorization.

7521061721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5880, while the sum is 32.

The square root of 7521061721 is about 86724.0550308852. The cubic root of 7521061721 is about 1959.2644158531.

Adding to 7521061721 its reverse (1271601257), we get a palindrome (8792662978).

The spelling of 7521061721 in words is "seven billion, five hundred twenty-one million, sixty-one thousand, seven hundred twenty-one".