811721210117 has 4 divisors (see below), whose sum is σ = 811730659980. Its totient is φ = 811711760256.

The previous prime is 811721210101. The next prime is 811721210137. The reversal of 811721210117 is 711012127118.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 477693851716 + 334027358401 = 691154^2 + 577951^2 .

It is a cyclic number.

It is not a de Polignac number, because 811721210117 - 2⁴ = 811721210101 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 (811721210137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4594892 + ... + 4768277.

It is an arithmetic number, because the mean of its divisors is an integer number (202932664995).

Almost surely, 2^811721210117 is an apocalyptic number.

It is an amenable number.

811721210117 is a deficient number, since it is larger than the sum of its proper divisors (9449863).

811721210117 is an equidigital number, since it uses as much as digits as its factorization.

811721210117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9449862.

The product of its (nonzero) digits is 1568, while the sum is 32.

The spelling of 811721210117 in words is "eight hundred eleven billion, seven hundred twenty-one million, two hundred ten thousand, one hundred seventeen".