78139440 has 120 divisors (see below), whose sum is σ = 268920288. Its totient is φ = 20321280.

The previous prime is 78139433. The next prime is 78139489. The reversal of 78139440 is 4493187.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×78139440² = 12211544167027200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 78139395 and 78139404.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28197 + ... + 30843.

Almost surely, 2^78139440 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 78139440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (134460144).

78139440 is an abundant number, since it is smaller than the sum of its proper divisors (190780848).

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

78139440 is a wasteful number, since it uses less digits than its factorization.

78139440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2707 (or 2698 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 78139440 is about 8839.6515768440. The cubic root of 78139440 is about 427.5203232361.

The spelling of 78139440 in words is "seventy-eight million, one hundred thirty-nine thousand, four hundred forty".