81729212 has 12 divisors (see below), whose sum is σ = 149244816. Its totient is φ = 39087840.

The previous prime is 81729211. The next prime is 81729227. The reversal of 81729212 is 21292718.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81729211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 444089 + ... + 444272.

It is an arithmetic number, because the mean of its divisors is an integer number (12437068).

Almost surely, 2^81729212 is an apocalyptic number.

It is an amenable number.

81729212 is a deficient number, since it is larger than the sum of its proper divisors (67515604).

81729212 is a wasteful number, since it uses less digits than its factorization.

81729212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888388 (or 888386 counting only the distinct ones).

The product of its digits is 4032, while the sum is 32.

The square root of 81729212 is about 9040.4210078956. The cubic root of 81729212 is about 433.9693962153.

The spelling of 81729212 in words is "eighty-one million, seven hundred twenty-nine thousand, two hundred twelve".