78138816 has 112 divisors (see below), whose sum is σ = 241499136. Its totient is φ = 21832704.

The previous prime is 78138779. The next prime is 78138871. The reversal of 78138816 is 61883187.

78138816 = 314² + 315² + ... + 642².

It is a tau number, because it is divible by the number of its divisors (112).

It is a super-2 number, since 2×78138816² = 12211349131763712, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62550 + ... + 63786.

Almost surely, 2^78138816 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 78138816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120749568).

78138816 is an abundant number, since it is smaller than the sum of its proper divisors (163360320).

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

78138816 is a wasteful number, since it uses less digits than its factorization.

78138816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1306 (or 1296 counting only the distinct ones).

The product of its digits is 64512, while the sum is 42.

The square root of 78138816 is about 8839.6162812647. The cubic root of 78138816 is about 427.5191852133.

The spelling of 78138816 in words is "seventy-eight million, one hundred thirty-eight thousand, eight hundred sixteen".