71981811 has 32 divisors (see below), whose sum is σ = 117354240. Its totient is φ = 43603560.

The previous prime is 71981797. The next prime is 71981813. The reversal of 71981811 is 11818917.

It is a happy number.

It is not a de Polignac number, because 71981811 - 2¹⁹ = 71457523 is a prime.

It is a super-2 number, since 2×71981811² = 10362762229679442, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (71981813) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34936 + ... + 36938.

It is an arithmetic number, because the mean of its divisors is an integer number (3667320).

Almost surely, 2^71981811 is an apocalyptic number.

71981811 is a deficient number, since it is larger than the sum of its proper divisors (45372429).

71981811 is a wasteful number, since it uses less digits than its factorization.

71981811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2045 (or 2017 counting only the distinct ones).

The product of its digits is 4032, while the sum is 36.

The square root of 71981811 is about 8484.2095094357. The cubic root of 71981811 is about 415.9817295816.

It can be divided in two parts, 7198 and 1811, that added together give a palindrome (9009).

The spelling of 71981811 in words is "seventy-one million, nine hundred eighty-one thousand, eight hundred eleven".