78987811 has 4 divisors (see below), whose sum is σ = 90271792. Its totient is φ = 67703832.

The previous prime is 78987809. The next prime is 78987829. The reversal of 78987811 is 11878987.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11878987 = 223 ⋅53269.

It is not a de Polignac number, because 78987811 - 2¹ = 78987809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78987611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5641980 + ... + 5641993.

It is an arithmetic number, because the mean of its divisors is an integer number (22567948).

Almost surely, 2^78987811 is an apocalyptic number.

78987811 is a deficient number, since it is larger than the sum of its proper divisors (11283981).

78987811 is a wasteful number, since it uses less digits than its factorization.

78987811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11283980.

The product of its digits is 225792, while the sum is 49.

The square root of 78987811 is about 8887.5087060436. The cubic root of 78987811 is about 429.0619736123.

The spelling of 78987811 in words is "seventy-eight million, nine hundred eighty-seven thousand, eight hundred eleven".