9951218681 has 4 divisors (see below), whose sum is σ = 9952097664. Its totient is φ = 9950339700.

The previous prime is 9951218653. The next prime is 9951218687. The reversal of 9951218681 is 1868121599.

9951218681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1868121599 = 883 ⋅2115653.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9951218681 is a prime.

It is a super-2 number, since 2×9951218681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (9951218687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 422285 + ... + 445226.

It is an arithmetic number, because the mean of its divisors is an integer number (2488024416).

Almost surely, 2^9951218681 is an apocalyptic number.

It is an amenable number.

9951218681 is a deficient number, since it is larger than the sum of its proper divisors (878983).

9951218681 is a wasteful number, since it uses less digits than its factorization.

9951218681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 878982.

The product of its digits is 311040, while the sum is 50.

The square root of 9951218681 is about 99755.7952251397. The cubic root of 9951218681 is about 2150.9257726484.

The spelling of 9951218681 in words is "nine billion, nine hundred fifty-one million, two hundred eighteen thousand, six hundred eighty-one".