811912221 has 8 divisors (see below), whose sum is σ = 1202832960. Its totient is φ = 541274796.

The previous prime is 811912219. The next prime is 811912223. The reversal of 811912221 is 122219118.

It is an interprime number because it is at equal distance from previous prime (811912219) and next prime (811912223).

It is not a de Polignac number, because 811912221 - 2¹ = 811912219 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 30070823 = 811912221 / (8 + 1 + 1 + 9 + 1 + 2 + 2 + 2 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811912223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15035385 + ... + 15035438.

It is an arithmetic number, because the mean of its divisors is an integer number (150354120).

Almost surely, 2^811912221 is an apocalyptic number.

It is an amenable number.

811912221 is a deficient number, since it is larger than the sum of its proper divisors (390920739).

811912221 is a wasteful number, since it uses less digits than its factorization.

811912221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30070832 (or 30070826 counting only the distinct ones).

The product of its digits is 576, while the sum is 27.

The square root of 811912221 is about 28494.0734364183. The cubic root of 811912221 is about 932.9027203917.

It can be divided in two parts, 8119 and 12221, that multiplied together give a palindrome (99222299).

The spelling of 811912221 in words is "eight hundred eleven million, nine hundred twelve thousand, two hundred twenty-one".