9918171421 has 4 divisors (see below), whose sum is σ = 9953977372. Its totient is φ = 9882365472.

The previous prime is 9918171413. The next prime is 9918171427. The reversal of 9918171421 is 1241718199.

9918171421 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 an emirpimes, since its reverse is a distinct semiprime: 1241718199 = 17 ⋅73042247.

It can be written as a sum of positive squares in 2 ways, for example, as 1743480025 + 8174691396 = 41755^2 + 90414^2 .

It is a cyclic number.

It is not a de Polignac number, because 9918171421 - 2³ = 9918171413 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 (9918171427) 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, 17902560 + ... + 17903113.

It is an arithmetic number, because the mean of its divisors is an integer number (2488494343).

Almost surely, 2^9918171421 is an apocalyptic number.

It is an amenable number.

9918171421 is a deficient number, since it is larger than the sum of its proper divisors (35805951).

9918171421 is a wasteful number, since it uses less digits than its factorization.

9918171421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35805950.

The product of its digits is 36288, while the sum is 43.

The square root of 9918171421 is about 99590.0166733594. The cubic root of 9918171421 is about 2148.5421103296.

The spelling of 9918171421 in words is "nine billion, nine hundred eighteen million, one hundred seventy-one thousand, four hundred twenty-one".