99639 has 6 divisors (see below), whose sum is σ = 143936. Its totient is φ = 66420.

The previous prime is 99623. The next prime is 99643. The reversal of 99639 is 93699.

It is not a de Polignac number, because 99639 - 2⁴ = 99623 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99679) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5527 + ... + 5544.

2⁹⁹⁶³⁹ is an apocalyptic number.

99639 is a deficient number, since it is larger than the sum of its proper divisors (44297).

99639 is a wasteful number, since it uses less digits than its factorization.

99639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11077 (or 11074 counting only the distinct ones).

The product of its digits is 13122, while the sum is 36.

The square root of 99639 is about 315.6564588283. The cubic root of 99639 is about 46.3599672047.

It can be divided in two parts, 996 and 39, that added together give a triangular number (1035 = T₄₅).

The spelling of 99639 in words is "ninety-nine thousand, six hundred thirty-nine".