99987978 has 8 divisors (see below), whose sum is σ = 199975968. Its totient is φ = 33329324.

The previous prime is 99987973. The next prime is 99987983. The reversal of 99987978 is 87978999.

It is an interprime number because it is at equal distance from previous prime (99987973) and next prime (99987983).

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

99987978 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (99987973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8332326 + ... + 8332337.

It is an arithmetic number, because the mean of its divisors is an integer number (24996996).

Almost surely, 2^99987978 is an apocalyptic number.

99987978 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

99987978 is a wasteful number, since it uses less digits than its factorization.

99987978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16664668.

The product of its digits is 20575296, while the sum is 66.

The square root of 99987978 is about 9999.3988819329. The cubic root of 99987978 is about 464.1402822222.

The spelling of 99987978 in words is "ninety-nine million, nine hundred eighty-seven thousand, nine hundred seventy-eight".