78405538 has 4 divisors (see below), whose sum is σ = 117608310. Its totient is φ = 39202768.

The previous prime is 78405527. The next prime is 78405599. The reversal of 78405538 is 83550487.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83550487 = 31 ⋅2695177.

It can be written as a sum of positive squares in only one way, i.e., 78375609 + 29929 = 8853^2 + 173^2 .

It is a super-2 number, since 2×78405538² = 12294856778138888, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 78405538.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19601383 + ... + 19601386.

Almost surely, 2^78405538 is an apocalyptic number.

78405538 is a deficient number, since it is larger than the sum of its proper divisors (39202772).

78405538 is a wasteful number, since it uses less digits than its factorization.

78405538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39202771.

The product of its (nonzero) digits is 134400, while the sum is 40.

The square root of 78405538 is about 8854.6901696220. The cubic root of 78405538 is about 428.0050695239.

The spelling of 78405538 in words is "seventy-eight million, four hundred five thousand, five hundred thirty-eight".