99721599 has 4 divisors (see below), whose sum is σ = 132962136. Its totient is φ = 66481064.

The previous prime is 99721591. The next prime is 99721603. The reversal of 99721599 is 99512799.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99512799 = 3 ⋅33170933.

It is a cyclic number.

It is not a de Polignac number, because 99721599 - 2³ = 99721591 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99721591) 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, 16620264 + ... + 16620269.

It is an arithmetic number, because the mean of its divisors is an integer number (33240534).

Almost surely, 2^99721599 is an apocalyptic number.

99721599 is a deficient number, since it is larger than the sum of its proper divisors (33240537).

99721599 is a wasteful number, since it uses less digits than its factorization.

99721599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33240536.

The product of its digits is 459270, while the sum is 51.

The square root of 99721599 is about 9986.0702481006. The cubic root of 99721599 is about 463.7277420218.

The spelling of 99721599 in words is "ninety-nine million, seven hundred twenty-one thousand, five hundred ninety-nine".