78494813 has 4 divisors (see below), whose sum is σ = 78928668. Its totient is φ = 78060960.

The previous prime is 78494809. The next prime is 78494863. The reversal of 78494813 is 31849487.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31849487 = 139 ⋅229133.

It can be written as a sum of positive squares in 2 ways, for example, as 14462809 + 64032004 = 3803^2 + 8002^2 .

It is a cyclic number.

It is not a de Polignac number, because 78494813 - 2² = 78494809 is a prime.

It is a super-2 number, since 2×78494813² = 12322871335809938, 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 (78494863) 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, 216656 + ... + 217017.

It is an arithmetic number, because the mean of its divisors is an integer number (19732167).

Almost surely, 2^78494813 is an apocalyptic number.

It is an amenable number.

78494813 is a deficient number, since it is larger than the sum of its proper divisors (433855).

78494813 is a wasteful number, since it uses less digits than its factorization.

78494813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 433854.

The product of its digits is 193536, while the sum is 44.

The square root of 78494813 is about 8859.7298491545. The cubic root of 78494813 is about 428.1674545641.

The spelling of 78494813 in words is "seventy-eight million, four hundred ninety-four thousand, eight hundred thirteen".