812121191 has 32 divisors (see below), whose sum is σ = 1007078400. Its totient is φ = 639555840.

The previous prime is 812121187. The next prime is 812121197. The reversal of 812121191 is 191121218.

It is not a de Polignac number, because 812121191 - 2² = 812121187 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 812121191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (812121197) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1311680 + ... + 1312298.

It is an arithmetic number, because the mean of its divisors is an integer number (31471200).

Almost surely, 2^812121191 is an apocalyptic number.

812121191 is a deficient number, since it is larger than the sum of its proper divisors (194957209).

812121191 is a wasteful number, since it uses less digits than its factorization.

812121191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 959.

The product of its digits is 288, while the sum is 26.

The square root of 812121191 is about 28497.7401033836. The cubic root of 812121191 is about 932.9827503726.

The spelling of 812121191 in words is "eight hundred twelve million, one hundred twenty-one thousand, one hundred ninety-one".