71978987 has 4 divisors (see below), whose sum is σ = 72107400. Its totient is φ = 71850576.

The previous prime is 71978981. The next prime is 71979001. The reversal of 71978987 is 78987917.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78987917 = 5281 ⋅14957.

It is a cyclic number.

It is not a de Polignac number, because 71978987 - 2¹⁴ = 71962603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71978981) 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, 63362 + ... + 64487.

It is an arithmetic number, because the mean of its divisors is an integer number (18026850).

Almost surely, 2^71978987 is an apocalyptic number.

71978987 is a deficient number, since it is larger than the sum of its proper divisors (128413).

71978987 is a wasteful number, since it uses less digits than its factorization.

71978987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128412.

The product of its digits is 1778112, while the sum is 56.

The square root of 71978987 is about 8484.0430809844. The cubic root of 71978987 is about 415.9762895602.

The spelling of 71978987 in words is "seventy-one million, nine hundred seventy-eight thousand, nine hundred eighty-seven".