78775391 has 8 divisors (see below), whose sum is σ = 84206304. Its totient is φ = 73511680.

The previous prime is 78775381. The next prime is 78775393. The reversal of 78775391 is 19357787.

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

It is a de Polignac number, because none of the positive numbers 2^k-78775391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78775393) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40826 + ... + 42711.

It is an arithmetic number, because the mean of its divisors is an integer number (10525788).

Almost surely, 2^78775391 is an apocalyptic number.

78775391 is a deficient number, since it is larger than the sum of its proper divisors (5430913).

78775391 is a wasteful number, since it uses less digits than its factorization.

78775391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83601.

The product of its digits is 370440, while the sum is 47.

The square root of 78775391 is about 8875.5501801297. The cubic root of 78775391 is about 428.6770063329.

The spelling of 78775391 in words is "seventy-eight million, seven hundred seventy-five thousand, three hundred ninety-one".