71507521 has 2 divisors, whose sum is σ = 71507522. Its totient is φ = 71507520.

The previous prime is 71507519. The next prime is 71507537. The reversal of 71507521 is 12570517.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66194496 + 5313025 = 8136^2 + 2305^2 .

It is an emirp because it is prime and its reverse (12570517) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71507521 - 2¹ = 71507519 is a prime.

It is a super-2 number, since 2×71507521² = 10226651119130882, which contains 22 as substring.

Together with 71507519, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 71507521.

It is not a weakly prime, because it can be changed into another prime (71507551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35753760 + 35753761.

It is an arithmetic number, because the mean of its divisors is an integer number (35753761).

Almost surely, 2^71507521 is an apocalyptic number.

It is an amenable number.

71507521 is a deficient number, since it is larger than the sum of its proper divisors (1).

71507521 is an equidigital number, since it uses as much as digits as its factorization.

71507521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2450, while the sum is 28.

The square root of 71507521 is about 8456.2119770025. The cubic root of 71507521 is about 415.0660774447.

The spelling of 71507521 in words is "seventy-one million, five hundred seven thousand, five hundred twenty-one".