851891039 has 4 divisors (see below), whose sum is σ = 852078624. Its totient is φ = 851703456.

The previous prime is 851891023. The next prime is 851891057. The reversal of 851891039 is 930198158.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 930198158 = 2 ⋅465099079.

It is a cyclic number.

It is not a de Polignac number, because 851891039 - 2⁴ = 851891023 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (851891069) 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, 86807 + ... + 96120.

It is an arithmetic number, because the mean of its divisors is an integer number (213019656).

Almost surely, 2^851891039 is an apocalyptic number.

851891039 is a deficient number, since it is larger than the sum of its proper divisors (187585).

851891039 is a wasteful number, since it uses less digits than its factorization.

851891039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187584.

The product of its (nonzero) digits is 77760, while the sum is 44.

The square root of 851891039 is about 29187.1725077987. The cubic root of 851891039 is about 947.9701957759.

The spelling of 851891039 in words is "eight hundred fifty-one million, eight hundred ninety-one thousand, thirty-nine".