81705429 has 40 divisors (see below), whose sum is σ = 135736832. Its totient is φ = 48638880.

The previous prime is 81705427. The next prime is 81705431. The reversal of 81705429 is 92450718.

It is an interprime number because it is at equal distance from previous prime (81705427) and next prime (81705431).

It is not a de Polignac number, because 81705429 - 2¹ = 81705427 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81705393 and 81705402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81705427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 31392 + ... + 33894.

Almost surely, 2^81705429 is an apocalyptic number.

It is an amenable number.

81705429 is a deficient number, since it is larger than the sum of its proper divisors (54031403).

81705429 is a wasteful number, since it uses less digits than its factorization.

81705429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2559 (or 2550 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 81705429 is about 9039.1055420324. The cubic root of 81705429 is about 433.9272974553.

The spelling of 81705429 in words is "eighty-one million, seven hundred five thousand, four hundred twenty-nine".