81906319 has 8 divisors (see below), whose sum is σ = 89889408. Its totient is φ = 74012760.

The previous prime is 81906299. The next prime is 81906329. The reversal of 81906319 is 91360918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81906319 - 2⁵ = 81906287 is a prime.

It is a super-2 number, since 2×81906319² = 13417290184259522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81906329) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20457 + ... + 24130.

It is an arithmetic number, because the mean of its divisors is an integer number (11236176).

Almost surely, 2^81906319 is an apocalyptic number.

81906319 is a deficient number, since it is larger than the sum of its proper divisors (7983089).

81906319 is a wasteful number, since it uses less digits than its factorization.

81906319 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44765.

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 81906319 is about 9050.2109920156. The cubic root of 81906319 is about 434.2826402601.

The spelling of 81906319 in words is "eighty-one million, nine hundred six thousand, three hundred nineteen".