78773813 has 4 divisors (see below), whose sum is σ = 78812748. Its totient is φ = 78734880.

The previous prime is 78773749. The next prime is 78773819. The reversal of 78773813 is 31837787.

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 41049649 + 37724164 = 6407^2 + 6142^2 .

It is a cyclic number.

It is not a de Polignac number, because 78773813 - 2⁶ = 78773749 is a prime.

It is a super-2 number, since 2×78773813² = 12410627229117938, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78773819) 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, 16256 + ... + 20537.

It is an arithmetic number, because the mean of its divisors is an integer number (19703187).

Almost surely, 2^78773813 is an apocalyptic number.

It is an amenable number.

78773813 is a deficient number, since it is larger than the sum of its proper divisors (38935).

78773813 is a wasteful number, since it uses less digits than its factorization.

78773813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38934.

The product of its digits is 197568, while the sum is 44.

The square root of 78773813 is about 8875.4612837869. The cubic root of 78773813 is about 428.6741439465.

The spelling of 78773813 in words is "seventy-eight million, seven hundred seventy-three thousand, eight hundred thirteen".