81764959 has 4 divisors (see below), whose sum is σ = 81784504. Its totient is φ = 81745416.

The previous prime is 81764941. The next prime is 81764981. The reversal of 81764959 is 95946718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81764959 - 2¹⁷ = 81633887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81764909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 672 + ... + 12805.

It is an arithmetic number, because the mean of its divisors is an integer number (20446126).

Almost surely, 2^81764959 is an apocalyptic number.

81764959 is a deficient number, since it is larger than the sum of its proper divisors (19545).

81764959 is a wasteful number, since it uses less digits than its factorization.

81764959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19544.

The product of its digits is 544320, while the sum is 49.

The square root of 81764959 is about 9042.3978567634. The cubic root of 81764959 is about 434.0326573286.

The spelling of 81764959 in words is "eighty-one million, seven hundred sixty-four thousand, nine hundred fifty-nine".