81948817 has 4 divisors (see below), whose sum is σ = 83337840. Its totient is φ = 80559796.

The previous prime is 81948781. The next prime is 81948859. The reversal of 81948817 is 71884918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81948817 - 2²³ = 73560209 is a prime.

It is a super-4 number, since 4×81948817⁴ (a number of 33 digits) contains 4444 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81948887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 694423 + ... + 694540.

It is an arithmetic number, because the mean of its divisors is an integer number (20834460).

Almost surely, 2^81948817 is an apocalyptic number.

It is an amenable number.

81948817 is a deficient number, since it is larger than the sum of its proper divisors (1389023).

81948817 is a wasteful number, since it uses less digits than its factorization.

81948817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1389022.

The product of its digits is 129024, while the sum is 46.

The square root of 81948817 is about 9052.5585885980. The cubic root of 81948817 is about 434.3577380577.

The spelling of 81948817 in words is "eighty-one million, nine hundred forty-eight thousand, eight hundred seventeen".