99987431 has 16 divisors (see below), whose sum is σ = 106813440. Its totient is φ = 93428640.

The previous prime is 99987373. The next prime is 99987449. The reversal of 99987431 is 13478999.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99987431 is a prime.

It is a super-2 number, since 2×99987431² = 19994972715959522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (50) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 99987431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99987131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 205070 + ... + 205556.

It is an arithmetic number, because the mean of its divisors is an integer number (6675840).

Almost surely, 2^99987431 is an apocalyptic number.

99987431 is a deficient number, since it is larger than the sum of its proper divisors (6826009).

99987431 is a wasteful number, since it uses less digits than its factorization.

99987431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 734.

The product of its digits is 489888, while the sum is 50.

The square root of 99987431 is about 9999.3715302513. The cubic root of 99987431 is about 464.1394358365.

The spelling of 99987431 in words is "ninety-nine million, nine hundred eighty-seven thousand, four hundred thirty-one".