78877391 has 4 divisors (see below), whose sum is σ = 78911832. Its totient is φ = 78842952.

The previous prime is 78877387. The next prime is 78877411. The reversal of 78877391 is 19377887.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19377887 = 29 ⋅668203.

It is a cyclic number.

It is not a de Polignac number, because 78877391 - 2² = 78877387 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 (78877691) 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, 13520 + ... + 18453.

It is an arithmetic number, because the mean of its divisors is an integer number (19727958).

Almost surely, 2^78877391 is an apocalyptic number.

78877391 is a deficient number, since it is larger than the sum of its proper divisors (34441).

78877391 is a wasteful number, since it uses less digits than its factorization.

78877391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34440.

The product of its digits is 592704, while the sum is 50.

The square root of 78877391 is about 8881.2944439423. The cubic root of 78877391 is about 428.8619464757.

The spelling of 78877391 in words is "seventy-eight million, eight hundred seventy-seven thousand, three hundred ninety-one".