81729551 has 8 divisors (see below), whose sum is σ = 83581200. Its totient is φ = 79889472.

The previous prime is 81729539. The next prime is 81729563. The reversal of 81729551 is 15592718.

It is an interprime number because it is at equal distance from previous prime (81729539) and next prime (81729563).

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 81729551 - 2²⁶ = 14620687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81729521) 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, 12275 + ... + 17723.

It is an arithmetic number, because the mean of its divisors is an integer number (10447650).

Almost surely, 2^81729551 is an apocalyptic number.

81729551 is a deficient number, since it is larger than the sum of its proper divisors (1851649).

81729551 is a wasteful number, since it uses less digits than its factorization.

81729551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5785.

The product of its digits is 25200, while the sum is 38.

The square root of 81729551 is about 9040.4397570030. The cubic root of 81729551 is about 433.9699962269.

The spelling of 81729551 in words is "eighty-one million, seven hundred twenty-nine thousand, five hundred fifty-one".