78647977 has 4 divisors (see below), whose sum is σ = 80773636. Its totient is φ = 76522320.

The previous prime is 78647957. The next prime is 78647981. The reversal of 78647977 is 77974687.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 55115776 + 23532201 = 7424^2 + 4851^2 .

It is a cyclic number.

It is not a de Polignac number, because 78647977 - 2¹⁵ = 78615209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78647957) 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, 1062774 + ... + 1062847.

It is an arithmetic number, because the mean of its divisors is an integer number (20193409).

Almost surely, 2^78647977 is an apocalyptic number.

It is an amenable number.

78647977 is a deficient number, since it is larger than the sum of its proper divisors (2125659).

78647977 is a wasteful number, since it uses less digits than its factorization.

78647977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2125658.

The product of its digits is 4148928, while the sum is 55.

The square root of 78647977 is about 8868.3694668186. The cubic root of 78647977 is about 428.4457626849.

The spelling of 78647977 in words is "seventy-eight million, six hundred forty-seven thousand, nine hundred seventy-seven".