78164640 has 288 divisors, whose sum is σ = 294368256. Its totient is φ = 18800640.

The previous prime is 78164627. The next prime is 78164641. The reversal of 78164640 is 4646187.

78164640 is a `hidden beast` number, since 7 + 8 + 1 + 6 + 4 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×78164640² = 12219421892659200, 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 = 78164595 and 78164604.

It is not an unprimeable number, because it can be changed into a prime (78164641) 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, 758829 + ... + 758931.

It is an arithmetic number, because the mean of its divisors is an integer number (1022112).

Almost surely, 2^78164640 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 78164640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147184128).

78164640 is an abundant number, since it is smaller than the sum of its proper divisors (216203616).

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

78164640 is a wasteful number, since it uses less digits than its factorization.

78164640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172 (or 161 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 78164640 is about 8841.0768574874. The cubic root of 78164640 is about 427.5662767870.

The spelling of 78164640 in words is "seventy-eight million, one hundred sixty-four thousand, six hundred forty".