818511668921 has 4 divisors (see below), whose sum is σ = 818532685200. Its totient is φ = 818490652644.

The previous prime is 818511668867. The next prime is 818511669007. The reversal of 818511668921 is 129866115818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 818511668921 - 2⁶ = 818511668857 is a prime.

It is a super-2 number, since 2×818511668921² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (818511268921) 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, 10449611 + ... + 10527648.

It is an arithmetic number, because the mean of its divisors is an integer number (204633171300).

Almost surely, 2^818511668921 is an apocalyptic number.

It is an amenable number.

818511668921 is a deficient number, since it is larger than the sum of its proper divisors (21016279).

818511668921 is a wasteful number, since it uses less digits than its factorization.

818511668921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21016278.

The product of its digits is 1658880, while the sum is 56.

The spelling of 818511668921 in words is "eight hundred eighteen billion, five hundred eleven million, six hundred sixty-eight thousand, nine hundred twenty-one".