81723039 has 8 divisors (see below), whose sum is σ = 110043312. Its totient is φ = 53942400.

The previous prime is 81722969. The next prime is 81723041. The reversal of 81723039 is 93032718.

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

It is not a de Polignac number, because 81723039 - 2⁷ = 81722911 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81723079) 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, 134554 + ... + 135159.

It is an arithmetic number, because the mean of its divisors is an integer number (13755414).

Almost surely, 2^81723039 is an apocalyptic number.

81723039 is a deficient number, since it is larger than the sum of its proper divisors (28320273).

81723039 is a wasteful number, since it uses less digits than its factorization.

81723039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269817.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 81723039 is about 9040.0795903576. The cubic root of 81723039 is about 433.9584700504.

It can be divided in two parts, 8172 and 3039, that added together give a palindrome (11211).

The spelling of 81723039 in words is "eighty-one million, seven hundred twenty-three thousand, thirty-nine".