78644308738 has 4 divisors (see below), whose sum is σ = 117966463110. Its totient is φ = 39322154368.

The previous prime is 78644308697. The next prime is 78644308789. The reversal of 78644308738 is 83780344687.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 56305120369 + 22339188369 = 237287^2 + 149463^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19661077183 + ... + 19661077186.

Almost surely, 2^78644308738 is an apocalyptic number.

78644308738 is a deficient number, since it is larger than the sum of its proper divisors (39322154372).

78644308738 is a wasteful number, since it uses less digits than its factorization.

78644308738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39322154371.

The product of its (nonzero) digits is 21676032, while the sum is 58.

The spelling of 78644308738 in words is "seventy-eight billion, six hundred forty-four million, three hundred eight thousand, seven hundred thirty-eight".