78109971 has 4 divisors (see below), whose sum is σ = 104146632. Its totient is φ = 52073312.

The previous prime is 78109943. The next prime is 78110009. The reversal of 78109971 is 17990187.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17990187 = 3 ⋅5996729.

It is a cyclic number.

It is not a de Polignac number, because 78109971 - 2⁵ = 78109939 is a prime.

It is a super-2 number, since 2×78109971² = 12202335139241682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78109921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13018326 + ... + 13018331.

It is an arithmetic number, because the mean of its divisors is an integer number (26036658).

Almost surely, 2^78109971 is an apocalyptic number.

78109971 is a deficient number, since it is larger than the sum of its proper divisors (26036661).

78109971 is a wasteful number, since it uses less digits than its factorization.

78109971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26036660.

The product of its (nonzero) digits is 31752, while the sum is 42.

The square root of 78109971 is about 8837.9845553158. The cubic root of 78109971 is about 427.4665724008.

The spelling of 78109971 in words is "seventy-eight million, one hundred nine thousand, nine hundred seventy-one".