71878981 has 4 divisors (see below), whose sum is σ = 72686700. Its totient is φ = 71071264.

The previous prime is 71878969. The next prime is 71879047. The reversal of 71878981 is 18987817.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18987817 = 139 ⋅136603.

It can be written as a sum of positive squares in 2 ways, for example, as 49126081 + 22752900 = 7009^2 + 4770^2 .

It is a cyclic number.

It is not a de Polignac number, because 71878981 - 2⁷ = 71878853 is a prime.

It is a super-2 number, since 2×71878981² = 10333175819196722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71878931) 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, 403726 + ... + 403903.

It is an arithmetic number, because the mean of its divisors is an integer number (18171675).

Almost surely, 2^71878981 is an apocalyptic number.

It is an amenable number.

71878981 is a deficient number, since it is larger than the sum of its proper divisors (807719).

71878981 is an equidigital number, since it uses as much as digits as its factorization.

71878981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 807718.

The product of its digits is 225792, while the sum is 49.

The square root of 71878981 is about 8478.1472622266. The cubic root of 71878981 is about 415.7835508758.

The spelling of 71878981 in words is "seventy-one million, eight hundred seventy-eight thousand, nine hundred eighty-one".