851091397 has 4 divisors (see below), whose sum is σ = 916559980. Its totient is φ = 785622816.

The previous prime is 851091361. The next prime is 851091433. The reversal of 851091397 is 793190158.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 793190158 = 2 ⋅396595079.

It is an interprime number because it is at equal distance from previous prime (851091361) and next prime (851091433).

It can be written as a sum of positive squares in 2 ways, for example, as 199769956 + 651321441 = 14134^2 + 25521^2 .

It is a cyclic number.

It is not a de Polignac number, because 851091397 - 2¹⁵ = 851058629 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 (851091097) 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, 32734272 + ... + 32734297.

It is an arithmetic number, because the mean of its divisors is an integer number (229139995).

Almost surely, 2^851091397 is an apocalyptic number.

It is an amenable number.

851091397 is a deficient number, since it is larger than the sum of its proper divisors (65468583).

851091397 is a wasteful number, since it uses less digits than its factorization.

851091397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65468582.

The product of its (nonzero) digits is 68040, while the sum is 43.

The square root of 851091397 is about 29173.4707739755. The cubic root of 851091397 is about 947.6734934772.

The spelling of 851091397 in words is "eight hundred fifty-one million, ninety-one thousand, three hundred ninety-seven".