856129091 has 4 divisors (see below), whose sum is σ = 857073912. Its totient is φ = 855184272.

The previous prime is 856129067. The next prime is 856129103. The reversal of 856129091 is 190921658.

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: 190921658 = 2 ⋅95460829.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-856129091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (856129031) 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, 471050 + ... + 472863.

It is an arithmetic number, because the mean of its divisors is an integer number (214268478).

Almost surely, 2^856129091 is an apocalyptic number.

856129091 is a deficient number, since it is larger than the sum of its proper divisors (944821).

856129091 is an equidigital number, since it uses as much as digits as its factorization.

856129091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944820.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 856129091 is about 29259.6837132598. The cubic root of 856129091 is about 949.5396073897.

The spelling of 856129091 in words is "eight hundred fifty-six million, one hundred twenty-nine thousand, ninety-one".