851538138671 has 4 divisors (see below), whose sum is σ = 928950696744. Its totient is φ = 774125580600.

The previous prime is 851538138643. The next prime is 851538138679. The reversal of 851538138671 is 176831835158.

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 851538138671 - 2²² = 851533944367 is a prime.

It is a super-2 number, since 2×851538138671² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (851538138679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38706279020 + ... + 38706279041.

It is an arithmetic number, because the mean of its divisors is an integer number (232237674186).

Almost surely, 2^851538138671 is an apocalyptic number.

851538138671 is a deficient number, since it is larger than the sum of its proper divisors (77412558073).

851538138671 is a wasteful number, since it uses less digits than its factorization.

851538138671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77412558072.

The product of its digits is 4838400, while the sum is 56.

The spelling of 851538138671 in words is "eight hundred fifty-one billion, five hundred thirty-eight million, one hundred thirty-eight thousand, six hundred seventy-one".