81722138 has 8 divisors (see below), whose sum is σ = 126537600. Its totient is φ = 39542940.

The previous prime is 81722129. The next prime is 81722149. The reversal of 81722138 is 83122718.

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

It is an unprimeable number.

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, 658988 + ... + 659111.

It is an arithmetic number, because the mean of its divisors is an integer number (15817200).

Almost surely, 2^81722138 is an apocalyptic number.

81722138 is a deficient number, since it is larger than the sum of its proper divisors (44815462).

81722138 is a wasteful number, since it uses less digits than its factorization.

81722138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1318132.

The product of its digits is 5376, while the sum is 32.

The square root of 81722138 is about 9040.0297565882. The cubic root of 81722138 is about 433.9568752410.

The spelling of 81722138 in words is "eighty-one million, seven hundred twenty-two thousand, one hundred thirty-eight".