8918724721 has 3 divisors (see below), whose sum is σ = 8918819161. Its totient is φ = 8918630282.

The previous prime is 8918724709. The next prime is 8918724751. The reversal of 8918724721 is 1274278198.

The square root of 8918724721 is 94439.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 8918724721 - 2²¹ = 8916627569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8918724751) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 47220 + ... + 141658.

Almost surely, 2^8918724721 is an apocalyptic number.

8918724721 is the 94439-th square number.

8918724721 is the 47220-th centered octagonal number.

It is an amenable number.

8918724721 is a deficient number, since it is larger than the sum of its proper divisors (94440).

8918724721 is an frugal number, since it uses more digits than its factorization.

8918724721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188878 (or 94439 counting only the distinct ones).

The product of its digits is 451584, while the sum is 49.

The cubic root of 8918724721 is about 2073.8034206993.

Multiplying 8918724721 by its sum of digits (49), we get a square (437017511329 = 661073²).

The spelling of 8918724721 in words is "eight billion, nine hundred eighteen million, seven hundred twenty-four thousand, seven hundred twenty-one".