78909138 has 144 divisors (see below), whose sum is σ = 227582784. Its totient is φ = 19192320.

The previous prime is 78909119. The next prime is 78909139. The reversal of 78909138 is 83190987.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 78909093 and 78909102.

It is not an unprimeable number, because it can be changed into a prime (78909139) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 400456 + ... + 400652.

It is an arithmetic number, because the mean of its divisors is an integer number (1580436).

Almost surely, 2^78909138 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78909138, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113791392).

78909138 is an abundant number, since it is smaller than the sum of its proper divisors (148673646).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

78909138 is a wasteful number, since it uses less digits than its factorization.

78909138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257 (or 237 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The square root of 78909138 is about 8883.0815599093. The cubic root of 78909138 is about 428.9194756520.

The spelling of 78909138 in words is "seventy-eight million, nine hundred nine thousand, one hundred thirty-eight".