81964559 has 2 divisors, whose sum is σ = 81964560. Its totient is φ = 81964558.

The previous prime is 81964543. The next prime is 81964567. The reversal of 81964559 is 95546918.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81964559 - 2⁴ = 81964543 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81964529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40982279 + 40982280.

It is an arithmetic number, because the mean of its divisors is an integer number (40982280).

Almost surely, 2^81964559 is an apocalyptic number.

81964559 is a deficient number, since it is larger than the sum of its proper divisors (1).

81964559 is an equidigital number, since it uses as much as digits as its factorization.

81964559 is an evil number, because the sum of its binary digits is even.

The product of its digits is 388800, while the sum is 47.

The square root of 81964559 is about 9053.4280247871. The cubic root of 81964559 is about 434.3855490011.

The spelling of 81964559 in words is "eighty-one million, nine hundred sixty-four thousand, five hundred fifty-nine".