78400784 has 60 divisors (see below), whose sum is σ = 192786768. Its totient is φ = 30542400.

The previous prime is 78400781. The next prime is 78400789. The reversal of 78400784 is 48700487.

It is a super-2 number, since 2×78400784² = 12293365863629312, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78400781) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4079 + ... + 13169.

Almost surely, 2^78400784 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 78400784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96393384).

78400784 is an abundant number, since it is smaller than the sum of its proper divisors (114385984).

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

78400784 is a wasteful number, since it uses less digits than its factorization.

78400784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9124 (or 9111 counting only the distinct ones).

The product of its (nonzero) digits is 50176, while the sum is 38.

The square root of 78400784 is about 8854.4217202480. The cubic root of 78400784 is about 427.9964188713.

Multiplying 78400784 by its sum of digits (38), we get a palindrome (2979229792).

It can be divided in two parts, 78400 and 784, that multiplied together give a square (61465600 = 7840²).

The spelling of 78400784 in words is "seventy-eight million, four hundred thousand, seven hundred eighty-four".