81917394 has 32 divisors (see below), whose sum is σ = 176783040. Its totient is φ = 25156032.

The previous prime is 81917393. The next prime is 81917447. The reversal of 81917394 is 49371918.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81917393) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73312 + ... + 74420.

It is an arithmetic number, because the mean of its divisors is an integer number (5524470).

Almost surely, 2^81917394 is an apocalyptic number.

81917394 is an abundant number, since it is smaller than the sum of its proper divisors (94865646).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81917394 is a wasteful number, since it uses less digits than its factorization.

81917394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2074.

The product of its digits is 54432, while the sum is 42.

The square root of 81917394 is about 9050.8228355216. The cubic root of 81917394 is about 434.3022132858.

The spelling of 81917394 in words is "eighty-one million, nine hundred seventeen thousand, three hundred ninety-four".