71133781 has 4 divisors (see below), whose sum is σ = 73586700. Its totient is φ = 68680864.

The previous prime is 71133773. The next prime is 71133787. The reversal of 71133781 is 18733117.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18733117 = 13 ⋅1441009.

It can be written as a sum of positive squares in 2 ways, for example, as 31820881 + 39312900 = 5641^2 + 6270^2 .

It is a cyclic number.

It is not a de Polignac number, because 71133781 - 2³ = 71133773 is a prime.

It is a super-2 number, since 2×71133781² = 10120029598711922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71133787) 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, 1226416 + ... + 1226473.

It is an arithmetic number, because the mean of its divisors is an integer number (18396675).

Almost surely, 2^71133781 is an apocalyptic number.

It is an amenable number.

71133781 is a deficient number, since it is larger than the sum of its proper divisors (2452919).

71133781 is a wasteful number, since it uses less digits than its factorization.

71133781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2452918.

The product of its digits is 3528, while the sum is 31.

The square root of 71133781 is about 8434.0844790647. The cubic root of 71133781 is about 414.3416881678.

Adding to 71133781 its reverse (18733117), we get a palindrome (89866898).

The spelling of 71133781 in words is "seventy-one million, one hundred thirty-three thousand, seven hundred eighty-one".