85781639 has 4 divisors (see below), whose sum is σ = 85920840. Its totient is φ = 85642440.

The previous prime is 85781621. The next prime is 85781687. The reversal of 85781639 is 93618758.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 85781639 - 2⁸ = 85781383 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 85781593 and 85781602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85781939) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68672 + ... + 69909.

It is an arithmetic number, because the mean of its divisors is an integer number (21480210).

Almost surely, 2^85781639 is an apocalyptic number.

85781639 is a deficient number, since it is larger than the sum of its proper divisors (139201).

85781639 is a wasteful number, since it uses less digits than its factorization.

85781639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139200.

The product of its digits is 362880, while the sum is 47.

The square root of 85781639 is about 9261.8377765970. The cubic root of 85781639 is about 441.0265956815.

The spelling of 85781639 in words is "eighty-five million, seven hundred eighty-one thousand, six hundred thirty-nine".