99381721 has 2 divisors, whose sum is σ = 99381722. Its totient is φ = 99381720.

The previous prime is 99381679. The next prime is 99381739. The reversal of 99381721 is 12718399.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 98505625 + 876096 = 9925^2 + 936^2 .

It is a cyclic number.

It is not a de Polignac number, because 99381721 - 2⁹ = 99381209 is a prime.

It is not a weakly prime, because it can be changed into another prime (99381221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49690860 + 49690861.

It is an arithmetic number, because the mean of its divisors is an integer number (49690861).

Almost surely, 2^99381721 is an apocalyptic number.

It is an amenable number.

99381721 is a deficient number, since it is larger than the sum of its proper divisors (1).

99381721 is an equidigital number, since it uses as much as digits as its factorization.

99381721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 40.

The square root of 99381721 is about 9969.0381180934. The cubic root of 99381721 is about 463.2003061104.

The spelling of 99381721 in words is "ninety-nine million, three hundred eighty-one thousand, seven hundred twenty-one".