71909881 has 4 divisors (see below), whose sum is σ = 76139892. Its totient is φ = 67679872.

The previous prime is 71909869. The next prime is 71909897. The reversal of 71909881 is 18890917.

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

It can be written as a sum of positive squares in 2 ways, for example, as 25452025 + 46457856 = 5045^2 + 6816^2 .

It is a cyclic number.

It is not a de Polignac number, because 71909881 - 2¹³ = 71901689 is a prime.

It is a super-2 number, since 2×71909881² = 10342061970868322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71909861) 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, 2114980 + ... + 2115013.

It is an arithmetic number, because the mean of its divisors is an integer number (19034973).

Almost surely, 2^71909881 is an apocalyptic number.

It is an amenable number.

71909881 is a deficient number, since it is larger than the sum of its proper divisors (4230011).

71909881 is a wasteful number, since it uses less digits than its factorization.

71909881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4230010.

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 71909881 is about 8479.9693985297. The cubic root of 71909881 is about 415.8431226307.

It can be divided in two parts, 7190 and 9881, that added together give a palindrome (17071).

The spelling of 71909881 in words is "seventy-one million, nine hundred nine thousand, eight hundred eighty-one".