99988721 has 4 divisors (see below), whose sum is σ = 114272832. Its totient is φ = 85704612.

The previous prime is 99988649. The next prime is 99988753. The reversal of 99988721 is 12788999.

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 not a de Polignac number, because 99988721 - 2¹⁸ = 99726577 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (99988771) 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, 7142045 + ... + 7142058.

It is an arithmetic number, because the mean of its divisors is an integer number (28568208).

Almost surely, 2^99988721 is an apocalyptic number.

It is an amenable number.

99988721 is a deficient number, since it is larger than the sum of its proper divisors (14284111).

99988721 is a wasteful number, since it uses less digits than its factorization.

99988721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14284110.

The product of its digits is 653184, while the sum is 53.

The square root of 99988721 is about 9999.4360340971. The cubic root of 99988721 is about 464.1414318783.

The spelling of 99988721 in words is "ninety-nine million, nine hundred eighty-eight thousand, seven hundred twenty-one".