71978 has 16 divisors (see below), whose sum is σ = 119880. Its totient is φ = 32256.

The previous prime is 71971. The next prime is 71983. The reversal of 71978 is 87917.

Added to its reverse (87917) it gives a triangular number (159895 = T₅₆₅).

It can be written as a sum of positive squares in 4 ways, for example, as 69169 + 2809 = 263^2 + 53^2 .

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (71971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 950 + ... + 1022.

2⁷¹⁹⁷⁸ is an apocalyptic number.

71978 is a deficient number, since it is larger than the sum of its proper divisors (47902).

71978 is a wasteful number, since it uses less digits than its factorization.

71978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121.

The product of its digits is 3528, while the sum is 32.

The square root of 71978 is about 268.2871595884. The cubic root of 71978 is about 41.5974388216.

Adding to 71978 its sum of digits (32), we get a triangular number (72010 = T₃₇₉).

Adding to 71978 its reverse (87917), we get a triangular number (159895 = T₅₆₅).

It can be divided in two parts, 719 and 78, that added together give a palindrome (797).

The spelling of 71978 in words is "seventy-one thousand, nine hundred seventy-eight".