81129312 has 72 divisors (see below), whose sum is σ = 251695080. Its totient is φ = 24583680.

The previous prime is 81129311. The next prime is 81129313. The reversal of 81129312 is 21392118.

It is an interprime number because it is at equal distance from previous prime (81129311) and next prime (81129313).

It is a tau number, because it is divible by the number of its divisors (72).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81129311) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9637 + ... + 15972.

It is an arithmetic number, because the mean of its divisors is an integer number (3495765).

Almost surely, 2^81129312 is an apocalyptic number.

It is an amenable number.

81129312 is an abundant number, since it is smaller than the sum of its proper divisors (170565768).

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

81129312 is a wasteful number, since it uses less digits than its factorization.

81129312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25636 (or 25625 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 81129312 is about 9007.1811350722. The cubic root of 81129312 is about 432.9049958066.

It can be divided in two parts, 8112 and 9312, that added together give a square (17424 = 132²).

The spelling of 81129312 in words is "eighty-one million, one hundred twenty-nine thousand, three hundred twelve".