811721172 has 24 divisors (see below), whose sum is σ = 1894527936. Its totient is φ = 270500608.

The previous prime is 811721167. The next prime is 811721177. The reversal of 811721172 is 271127118.

It is an interprime number because it is at equal distance from previous prime (811721167) and next prime (811721177).

It is a super-2 number, since 2×811721172² = 1317782522146107168, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811721177) 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, 55273 + ... + 68399.

It is an arithmetic number, because the mean of its divisors is an integer number (78938664).

Almost surely, 2^811721172 is an apocalyptic number.

It is an amenable number.

811721172 is an abundant number, since it is smaller than the sum of its proper divisors (1082806764).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

811721172 is a wasteful number, since it uses less digits than its factorization.

811721172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18287 (or 18285 counting only the distinct ones).

The product of its digits is 1568, while the sum is 30.

The square root of 811721172 is about 28490.7208052025. The cubic root of 811721172 is about 932.8295416626.

The spelling of 811721172 in words is "eight hundred eleven million, seven hundred twenty-one thousand, one hundred seventy-two".