78839640 has 192 divisors, whose sum is σ = 286640640. Its totient is φ = 18627840.

The previous prime is 78839627. The next prime is 78839641. The reversal of 78839640 is 4693887.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78839641) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 170049 + ... + 170511.

It is an arithmetic number, because the mean of its divisors is an integer number (1492920).

Almost surely, 2^78839640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78839640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143320320).

78839640 is an abundant number, since it is smaller than the sum of its proper divisors (207801000).

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

78839640 is a wasteful number, since it uses less digits than its factorization.

78839640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534 (or 527 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 78839640 is about 8879.1688800248. The cubic root of 78839640 is about 428.7935172732.

Subtracting from 78839640 its reverse (4693887), we obtain a triangular number (74145753 = T₁₂₁₇₇).

The spelling of 78839640 in words is "seventy-eight million, eight hundred thirty-nine thousand, six hundred forty".