78129728 has 14 divisors (see below), whose sum is σ = 155038806. Its totient is φ = 39064832.

The previous prime is 78129721. The next prime is 78129761. The reversal of 78129728 is 82792187.

It can be written as a sum of positive squares in only one way, i.e., 74097664 + 4032064 = 8608^2 + 2008^2 .

It is a super-2 number, since 2×78129728² = 12208508794707968, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78129721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610325 + ... + 610452.

Almost surely, 2^78129728 is an apocalyptic number.

It is an amenable number.

78129728 is a deficient number, since it is larger than the sum of its proper divisors (76909078).

78129728 is a wasteful number, since it uses less digits than its factorization.

78129728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1220789 (or 1220779 counting only the distinct ones).

The product of its digits is 112896, while the sum is 44.

The square root of 78129728 is about 8839.1022168544. The cubic root of 78129728 is about 427.5026102459.

The spelling of 78129728 in words is "seventy-eight million, one hundred twenty-nine thousand, seven hundred twenty-eight".