71231681 has 2 divisors, whose sum is σ = 71231682. Its totient is φ = 71231680.

The previous prime is 71231669. The next prime is 71231723. The reversal of 71231681 is 18613217.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65351056 + 5880625 = 8084^2 + 2425^2 .

It is a cyclic number.

It is not a de Polignac number, because 71231681 - 2⁶ = 71231617 is a prime.

It is a super-2 number, since 2×71231681² = 10147904756171522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (71230681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35615840 + 35615841.

It is an arithmetic number, because the mean of its divisors is an integer number (35615841).

Almost surely, 2^71231681 is an apocalyptic number.

It is an amenable number.

71231681 is a deficient number, since it is larger than the sum of its proper divisors (1).

71231681 is an equidigital number, since it uses as much as digits as its factorization.

71231681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 71231681 is about 8439.8863144002. The cubic root of 71231681 is about 414.5316844244.

Adding to 71231681 its reverse (18613217), we get a palindrome (89844898).

The spelling of 71231681 in words is "seventy-one million, two hundred thirty-one thousand, six hundred eighty-one".