85121639 has 4 divisors (see below), whose sum is σ = 87101256. Its totient is φ = 83142024.

The previous prime is 85121609. The next prime is 85121651. The reversal of 85121639 is 93612158.

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 85121639 - 2⁸ = 85121383 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 85121599 and 85121608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85121609) 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, 989744 + ... + 989829.

It is an arithmetic number, because the mean of its divisors is an integer number (21775314).

Almost surely, 2^85121639 is an apocalyptic number.

85121639 is a deficient number, since it is larger than the sum of its proper divisors (1979617).

85121639 is a wasteful number, since it uses less digits than its factorization.

85121639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1979616.

The product of its digits is 12960, while the sum is 35.

The square root of 85121639 is about 9226.1388998866. The cubic root of 85121639 is about 439.8926029204.

The spelling of 85121639 in words is "eighty-five million, one hundred twenty-one thousand, six hundred thirty-nine".