78911987 has 16 divisors (see below), whose sum is σ = 101779200. Its totient is φ = 59367840.

The previous prime is 78911981. The next prime is 78911993.

78911987 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (78911981) and next prime (78911993).

It is not a de Polignac number, because 78911987 - 2¹⁶ = 78846451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78911981) 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, 15437 + ... + 19902.

It is an arithmetic number, because the mean of its divisors is an integer number (6361200).

Almost surely, 2^78911987 is an apocalyptic number.

78911987 is a gapful number since it is divisible by the number (77) formed by its first and last digit.

78911987 is a deficient number, since it is larger than the sum of its proper divisors (22867213).

78911987 is a wasteful number, since it uses less digits than its factorization.

78911987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35386.

The product of its digits is 254016, while the sum is 50.

The square root of 78911987 is about 8883.2419194796. The cubic root of 78911987 is about 428.9246376096.

The spelling of 78911987 in words is "seventy-eight million, nine hundred eleven thousand, nine hundred eighty-seven".