99981591 has 8 divisors (see below), whose sum is σ = 140325120. Its totient is φ = 63146232.

The previous prime is 99981571. The next prime is 99981593. The reversal of 99981591 is 19518999.

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

It is not a de Polignac number, because 99981591 - 2¹³ = 99973399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99981593) 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, 876975 + ... + 877088.

It is an arithmetic number, because the mean of its divisors is an integer number (17540640).

Almost surely, 2^99981591 is an apocalyptic number.

99981591 is a deficient number, since it is larger than the sum of its proper divisors (40343529).

99981591 is a wasteful number, since it uses less digits than its factorization.

99981591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1754085.

The product of its digits is 262440, while the sum is 51.

The square root of 99981591 is about 9999.0795076347. The cubic root of 99981591 is about 464.1303992770.

The spelling of 99981591 in words is "ninety-nine million, nine hundred eighty-one thousand, five hundred ninety-one".