78171440 has 80 divisors (see below), whose sum is σ = 194050080. Its totient is φ = 29184000.

The previous prime is 78171409. The next prime is 78171517. The reversal of 78171440 is 4417187.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×78171440² = 12221548063347200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 78171397 and 78171406.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 311315 + ... + 311565.

It is an arithmetic number, because the mean of its divisors is an integer number (2425626).

Almost surely, 2^78171440 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 78171440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97025040).

78171440 is an abundant number, since it is smaller than the sum of its proper divisors (115878640).

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

78171440 is a wasteful number, since it uses less digits than its factorization.

78171440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510 (or 504 counting only the distinct ones).

The product of its (nonzero) digits is 6272, while the sum is 32.

The square root of 78171440 is about 8841.4614176617. The cubic root of 78171440 is about 427.5786752593.

The spelling of 78171440 in words is "seventy-eight million, one hundred seventy-one thousand, four hundred forty".