99855591 has 8 divisors (see below), whose sum is σ = 145244544. Its totient is φ = 60518520.

The previous prime is 99855571. The next prime is 99855617. The reversal of 99855591 is 19555899.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 99855591 - 2¹³ = 99847399 is a prime.

It is a super-2 number, since 2×99855591² = 19942278107918562, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99855521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1512931 + ... + 1512996.

It is an arithmetic number, because the mean of its divisors is an integer number (18155568).

Almost surely, 2^99855591 is an apocalyptic number.

99855591 is a deficient number, since it is larger than the sum of its proper divisors (45388953).

99855591 is a wasteful number, since it uses less digits than its factorization.

99855591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3025941.

The product of its digits is 729000, while the sum is 51.

The square root of 99855591 is about 9992.7769413712. The cubic root of 99855591 is about 463.9353466571.

It can be divided in two parts, 9985 and 5591, that added together give a triangular number (15576 = T₁₇₆).

The spelling of 99855591 in words is "ninety-nine million, eight hundred fifty-five thousand, five hundred ninety-one".