7531721557 has 2 divisors, whose sum is σ = 7531721558. Its totient is φ = 7531721556.

The previous prime is 7531721537. The next prime is 7531721579. The reversal of 7531721557 is 7551271357.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7497135396 + 34586161 = 86586^2 + 5881^2 .

It is a cyclic number.

It is not a de Polignac number, because 7531721557 - 2¹¹ = 7531719509 is a prime.

It is a super-2 number, since 2×7531721557² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7531721537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3765860778 + 3765860779.

It is an arithmetic number, because the mean of its divisors is an integer number (3765860779).

Almost surely, 2^7531721557 is an apocalyptic number.

It is an amenable number.

7531721557 is a deficient number, since it is larger than the sum of its proper divisors (1).

7531721557 is an equidigital number, since it uses as much as digits as its factorization.

7531721557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 257250, while the sum is 43.

The square root of 7531721557 is about 86785.4916273452. The cubic root of 7531721557 is about 1960.1896211276.

The spelling of 7531721557 in words is "seven billion, five hundred thirty-one million, seven hundred twenty-one thousand, five hundred fifty-seven".