77521 has 2 divisors, whose sum is σ = 77522. Its totient is φ = 77520.

The previous prime is 77513. The next prime is 77527. The reversal of 77521 is 12577.

77521 is nontrivially palindromic in base 13.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 50625 + 26896 = 225^2 + 164^2 .

It is an emirp because it is prime and its reverse (12577) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77521 - 2³ = 77513 is a prime.

It is a Chen prime.

77521 is a lucky number.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 77492 and 77501.

It is not a weakly prime, because it can be changed into another prime (77527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38760 + 38761.

It is an arithmetic number, because the mean of its divisors is an integer number (38761).

2⁷⁷⁵²¹ is an apocalyptic number.

It is an amenable number.

77521 is a deficient number, since it is larger than the sum of its proper divisors (1).

77521 is an equidigital number, since it uses as much as digits as its factorization.

77521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 490, while the sum is 22.

The square root of 77521 is about 278.4259327002. The cubic root of 77521 is about 42.6389454804.

The spelling of 77521 in words is "seventy-seven thousand, five hundred twenty-one".