78507521 has 2 divisors, whose sum is σ = 78507522. Its totient is φ = 78507520.

The previous prime is 78507491. The next prime is 78507587. The reversal of 78507521 is 12570587.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78499600 + 7921 = 8860^2 + 89^2 .

It is a cyclic number.

It is not a de Polignac number, because 78507521 - 2¹⁴ = 78491137 is a prime.

It is not a weakly prime, because it can be changed into another prime (78507421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39253760 + 39253761.

It is an arithmetic number, because the mean of its divisors is an integer number (39253761).

Almost surely, 2^78507521 is an apocalyptic number.

It is an amenable number.

78507521 is a deficient number, since it is larger than the sum of its proper divisors (1).

78507521 is an equidigital number, since it uses as much as digits as its factorization.

78507521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19600, while the sum is 35.

The square root of 78507521 is about 8860.4469977536. The cubic root of 78507521 is about 428.1905595235.

The spelling of 78507521 in words is "seventy-eight million, five hundred seven thousand, five hundred twenty-one".