851871961 has 4 divisors (see below), whose sum is σ = 851930752. Its totient is φ = 851813172.

The previous prime is 851871877. The next prime is 851871983. The reversal of 851871961 is 169178158.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 169178158 = 2 ⋅84589079.

It is a cyclic number.

It is not a de Polignac number, because 851871961 - 2¹¹ = 851869913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (851821961) 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, 9460 + ... + 42346.

It is an arithmetic number, because the mean of its divisors is an integer number (212982688).

Almost surely, 2^851871961 is an apocalyptic number.

It is an amenable number.

851871961 is a deficient number, since it is larger than the sum of its proper divisors (58791).

851871961 is a wasteful number, since it uses less digits than its factorization.

851871961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58790.

The product of its digits is 120960, while the sum is 46.

The square root of 851871961 is about 29186.8456843147. The cubic root of 851871961 is about 947.9631191626.

The spelling of 851871961 in words is "eight hundred fifty-one million, eight hundred seventy-one thousand, nine hundred sixty-one".