99999431280 has 600 divisors, whose sum is σ = 421613720352. Its totient is φ = 21861633024.

The previous prime is 99999431263. The next prime is 99999431281. The reversal of 99999431280 is 8213499999.

99999431280 is a `hidden beast` number, since 9 + 99 + 99 + 431 + 28 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99999431281) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 7296114 + ... + 7309806.

Almost surely, 2^99999431280 is an apocalyptic number.

99999431280 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

99999431280 is the 182574-th octagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 99999431280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (210806860176).

99999431280 is an abundant number, since it is smaller than the sum of its proper divisors (321614289072).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

99999431280 is a wasteful number, since it uses less digits than its factorization.

99999431280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13755 (or 13733 counting only the distinct ones).

The product of its (nonzero) digits is 11337408, while the sum is 63.

The spelling of 99999431280 in words is "ninety-nine billion, nine hundred ninety-nine million, four hundred thirty-one thousand, two hundred eighty".