81464521 has 2 divisors, whose sum is σ = 81464522. Its totient is φ = 81464520.

The previous prime is 81464503. The next prime is 81464543. The reversal of 81464521 is 12546418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75012921 + 6451600 = 8661^2 + 2540^2 .

It is a cyclic number.

It is not a de Polignac number, because 81464521 - 2¹¹ = 81462473 is a prime.

It is not a weakly prime, because it can be changed into another prime (81464821) 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, 40732260 + 40732261.

It is an arithmetic number, because the mean of its divisors is an integer number (40732261).

Almost surely, 2^81464521 is an apocalyptic number.

It is an amenable number.

81464521 is a deficient number, since it is larger than the sum of its proper divisors (1).

81464521 is an equidigital number, since it uses as much as digits as its factorization.

81464521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7680, while the sum is 31.

The square root of 81464521 is about 9025.7698286628. The cubic root of 81464521 is about 433.5004002095.

The spelling of 81464521 in words is "eighty-one million, four hundred sixty-four thousand, five hundred twenty-one".