78440818 has 4 divisors (see below), whose sum is σ = 117661230. Its totient is φ = 39220408.

The previous prime is 78440807. The next prime is 78440821. The reversal of 78440818 is 81804487.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81804487 = 47 ⋅1740521.

It can be written as a sum of positive squares in only one way, i.e., 76090729 + 2350089 = 8723^2 + 1533^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19610203 + ... + 19610206.

Almost surely, 2^78440818 is an apocalyptic number.

78440818 is a deficient number, since it is larger than the sum of its proper divisors (39220412).

78440818 is a wasteful number, since it uses less digits than its factorization.

78440818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39220411.

The product of its (nonzero) digits is 57344, while the sum is 40.

The square root of 78440818 is about 8856.6821101358. The cubic root of 78440818 is about 428.0692561233.

It can be divided in two parts, 78 and 440818, that added together give a square (440896 = 664²).

The spelling of 78440818 in words is "seventy-eight million, four hundred forty thousand, eight hundred eighteen".