78189745 has 4 divisors (see below), whose sum is σ = 93827700. Its totient is φ = 62551792.

The previous prime is 78189743. The next prime is 78189751. The reversal of 78189745 is 54798187.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54798187 = 859 ⋅63793.

It can be written as a sum of positive squares in 2 ways, for example, as 54287424 + 23902321 = 7368^2 + 4889^2 .

It is a cyclic number.

It is not a de Polignac number, because 78189745 - 2¹ = 78189743 is a prime.

It is a super-2 number, since 2×78189745² = 12227272446330050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (78189743) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 7818970 + ... + 7818979.

It is an arithmetic number, because the mean of its divisors is an integer number (23456925).

Almost surely, 2^78189745 is an apocalyptic number.

It is an amenable number.

78189745 is a deficient number, since it is larger than the sum of its proper divisors (15637955).

78189745 is a wasteful number, since it uses less digits than its factorization.

78189745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15637954.

The product of its digits is 564480, while the sum is 49.

The square root of 78189745 is about 8842.4965366123. The cubic root of 78189745 is about 427.6120472803.

The spelling of 78189745 in words is "seventy-eight million, one hundred eighty-nine thousand, seven hundred forty-five".