81643429 has 8 divisors (see below), whose sum is σ = 96316928. Its totient is φ = 67722480.

The previous prime is 81643427. The next prime is 81643459. The reversal of 81643429 is 92434618.

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

It is not a de Polignac number, because 81643429 - 2¹ = 81643427 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 (81643427) 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, 187902 + ... + 188335.

It is an arithmetic number, because the mean of its divisors is an integer number (12039616).

Almost surely, 2^81643429 is an apocalyptic number.

It is an amenable number.

81643429 is a deficient number, since it is larger than the sum of its proper divisors (14673499).

81643429 is a wasteful number, since it uses less digits than its factorization.

81643429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 376275.

The product of its digits is 41472, while the sum is 37.

The square root of 81643429 is about 9035.6753483068. The cubic root of 81643429 is about 433.8175116037.

The spelling of 81643429 in words is "eighty-one million, six hundred forty-three thousand, four hundred twenty-nine".