99999780 has 144 divisors (see below), whose sum is σ = 305329920. Its totient is φ = 24440832.

The previous prime is 99999773. The next prime is 99999787. The reversal of 99999780 is 8799999.

It is an interprime number because it is at equal distance from previous prime (99999773) and next prime (99999787).

It is a Harshad number since it is a multiple of its sum of digits (60).

It is not an unprimeable number, because it can be changed into a prime (99999787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1265781 + ... + 1265859.

Almost surely, 2^99999780 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 99999780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (152664960).

99999780 is an abundant number, since it is smaller than the sum of its proper divisors (205330140).

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

99999780 is a wasteful number, since it uses less digits than its factorization.

99999780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198 (or 179 counting only the distinct ones).

The product of its (nonzero) digits is 3306744, while the sum is 60.

The square root of 99999780 is about 9999.9889999939. The cubic root of 99999780 is about 464.1585429778.

The spelling of 99999780 in words is "ninety-nine million, nine hundred ninety-nine thousand, seven hundred eighty".