9918642252721 has 4 divisors (see below), whose sum is σ = 9925385042944. Its totient is φ = 9911899462500.

The previous prime is 9918642252683. The next prime is 9918642252733. The reversal of 9918642252721 is 1272522468199.

9918642252721 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.

It is a cyclic number.

It is not a de Polignac number, because 9918642252721 - 2²⁵ = 9918608698289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9918642252791) 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, 3371392905 + ... + 3371395846.

It is an arithmetic number, because the mean of its divisors is an integer number (2481346260736).

Almost surely, 2^{9918642252721} is an apocalyptic number.

It is an amenable number.

9918642252721 is a deficient number, since it is larger than the sum of its proper divisors (6742790223).

9918642252721 is a wasteful number, since it uses less digits than its factorization.

9918642252721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6742790222.

The product of its digits is 8709120, while the sum is 58.

The spelling of 9918642252721 in words is "nine trillion, nine hundred eighteen billion, six hundred forty-two million, two hundred fifty-two thousand, seven hundred twenty-one".