99717721 has 2 divisors, whose sum is σ = 99717722. Its totient is φ = 99717720.

The previous prime is 99717707. The next prime is 99717749. The reversal of 99717721 is 12771799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 58308496 + 41409225 = 7636^2 + 6435^2 .

It is an emirp because it is prime and its reverse (12771799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 99717721 - 2²¹ = 97620569 is a prime.

It is not a weakly prime, because it can be changed into another prime (99717791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49858860 + 49858861.

It is an arithmetic number, because the mean of its divisors is an integer number (49858861).

Almost surely, 2^99717721 is an apocalyptic number.

It is an amenable number.

99717721 is a deficient number, since it is larger than the sum of its proper divisors (1).

99717721 is an equidigital number, since it uses as much as digits as its factorization.

99717721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55566, while the sum is 43.

The square root of 99717721 is about 9985.8760757382. The cubic root of 99717721 is about 463.7217307548.

The spelling of 99717721 in words is "ninety-nine million, seven hundred seventeen thousand, seven hundred twenty-one".