78128091 has 32 divisors (see below), whose sum is σ = 120268800. Its totient is φ = 50073120.

The previous prime is 78128081. The next prime is 78128131. The reversal of 78128091 is 19082187.

It is not a de Polignac number, because 78128091 - 2¹⁴ = 78111707 is a prime.

It is a super-2 number, since 2×78128091² = 12207997206608562, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78128021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 224980 + ... + 225326.

It is an arithmetic number, because the mean of its divisors is an integer number (3758400).

Almost surely, 2^78128091 is an apocalyptic number.

78128091 is a deficient number, since it is larger than the sum of its proper divisors (42140709).

78128091 is a wasteful number, since it uses less digits than its factorization.

78128091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656 (or 650 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 78128091 is about 8839.0096164672. The cubic root of 78128091 is about 427.4996244995.

The spelling of 78128091 in words is "seventy-eight million, one hundred twenty-eight thousand, ninety-one".