78009291 has 8 divisors (see below), whose sum is σ = 115569360. Its totient is φ = 52006176.

The previous prime is 78009289. The next prime is 78009317. The reversal of 78009291 is 19290087.

It is a happy number.

It is not a de Polignac number, because 78009291 - 2¹ = 78009289 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78009221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1444590 + ... + 1444643.

It is an arithmetic number, because the mean of its divisors is an integer number (14446170).

Almost surely, 2^78009291 is an apocalyptic number.

78009291 is a deficient number, since it is larger than the sum of its proper divisors (37560069).

78009291 is a wasteful number, since it uses less digits than its factorization.

78009291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2889242 (or 2889236 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 78009291 is about 8832.2868499613. The cubic root of 78009291 is about 427.2828321423.

The spelling of 78009291 in words is "seventy-eight million, nine thousand, two hundred ninety-one".