81665429 has 8 divisors (see below), whose sum is σ = 83036160. Its totient is φ = 80299296.

The previous prime is 81665413. The next prime is 81665447. The reversal of 81665429 is 92456618.

It is a happy number.

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 81665429 - 2⁴ = 81665413 is a prime.

It is a super-3 number, since 3×81665429³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81665489) 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, 63212 + ... + 64490.

It is an arithmetic number, because the mean of its divisors is an integer number (10379520).

Almost surely, 2^81665429 is an apocalyptic number.

It is an amenable number.

81665429 is a deficient number, since it is larger than the sum of its proper divisors (1370731).

81665429 is a wasteful number, since it uses less digits than its factorization.

81665429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2299.

The product of its digits is 103680, while the sum is 41.

The square root of 81665429 is about 9036.8926628571. The cubic root of 81665429 is about 433.8564742336.

The spelling of 81665429 in words is "eighty-one million, six hundred sixty-five thousand, four hundred twenty-nine".