85729909 has 2 divisors, whose sum is σ = 85729910. Its totient is φ = 85729908.

The previous prime is 85729907. The next prime is 85729921. The reversal of 85729909 is 90992758.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57608100 + 28121809 = 7590^2 + 5303^2 .

It is a cyclic number.

It is not a de Polignac number, because 85729909 - 2¹ = 85729907 is a prime.

Together with 85729907, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (85729907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42864954 + 42864955.

It is an arithmetic number, because the mean of its divisors is an integer number (42864955).

Almost surely, 2^85729909 is an apocalyptic number.

It is an amenable number.

85729909 is a deficient number, since it is larger than the sum of its proper divisors (1).

85729909 is an equidigital number, since it uses as much as digits as its factorization.

85729909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 408240, while the sum is 49.

The square root of 85729909 is about 9259.0447131440. The cubic root of 85729909 is about 440.9379252169.

It can be divided in two parts, 8572 and 9909, that added together give a palindrome (18481).

The spelling of 85729909 in words is "eighty-five million, seven hundred twenty-nine thousand, nine hundred nine".