78189971 has 4 divisors (see below), whose sum is σ = 79068600. Its totient is φ = 77311344.

The previous prime is 78189913. The next prime is 78189973. The reversal of 78189971 is 17998187.

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

It is a cyclic number.

It is not a de Polignac number, because 78189971 - 2¹⁴ = 78173587 is a prime.

It is a super-2 number, since 2×78189971² = 12227343129961682, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (78189973) 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, 439181 + ... + 439358.

It is an arithmetic number, because the mean of its divisors is an integer number (19767150).

Almost surely, 2^78189971 is an apocalyptic number.

78189971 is a deficient number, since it is larger than the sum of its proper divisors (878629).

78189971 is an equidigital number, since it uses as much as digits as its factorization.

78189971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878628.

The product of its digits is 254016, while the sum is 50.

The square root of 78189971 is about 8842.5093157994. The cubic root of 78189971 is about 427.6124592705.

The spelling of 78189971 in words is "seventy-eight million, one hundred eighty-nine thousand, nine hundred seventy-one".