81629745 has 16 divisors (see below), whose sum is σ = 132822720. Its totient is φ = 42797504.

The previous prime is 81629707. The next prime is 81629749. The reversal of 81629745 is 54792618.

It is a cyclic number.

It is not a de Polignac number, because 81629745 - 2¹⁶ = 81564209 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81629697 and 81629706.

It is not an unprimeable number, because it can be changed into a prime (81629749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45234 + ... + 47003.

It is an arithmetic number, because the mean of its divisors is an integer number (8301420).

Almost surely, 2^81629745 is an apocalyptic number.

It is an amenable number.

81629745 is a deficient number, since it is larger than the sum of its proper divisors (51192975).

81629745 is a wasteful number, since it uses less digits than its factorization.

81629745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92304.

The product of its digits is 120960, while the sum is 42.

The square root of 81629745 is about 9034.9180959210. The cubic root of 81629745 is about 433.7932733170.

The spelling of 81629745 in words is "eighty-one million, six hundred twenty-nine thousand, seven hundred forty-five".