78091998 has 8 divisors (see below), whose sum is σ = 156184008. Its totient is φ = 26030664.

The previous prime is 78091991. The next prime is 78092009. The reversal of 78091998 is 89919087.

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

78091998 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 78091998.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78091991) 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, 6507661 + ... + 6507672.

It is an arithmetic number, because the mean of its divisors is an integer number (19523001).

Almost surely, 2^78091998 is an apocalyptic number.

78091998 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.

78091998 is a wasteful number, since it uses less digits than its factorization.

78091998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13015338.

The product of its (nonzero) digits is 326592, while the sum is 51.

The square root of 78091998 is about 8836.9676925968. The cubic root of 78091998 is about 427.4337833900.

The spelling of 78091998 in words is "seventy-eight million, ninety-one thousand, nine hundred ninety-eight".