81293237 has 2 divisors, whose sum is σ = 81293238. Its totient is φ = 81293236.

The previous prime is 81293161. The next prime is 81293243. The reversal of 81293237 is 73239218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60078001 + 21215236 = 7751^2 + 4606^2 .

It is a cyclic number.

It is not a de Polignac number, because 81293237 - 2²⁴ = 64516021 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81293197 and 81293206.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81293257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40646618 + 40646619.

It is an arithmetic number, because the mean of its divisors is an integer number (40646619).

Almost surely, 2^81293237 is an apocalyptic number.

It is an amenable number.

81293237 is a deficient number, since it is larger than the sum of its proper divisors (1).

81293237 is an equidigital number, since it uses as much as digits as its factorization.

81293237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 35.

The square root of 81293237 is about 9016.2762269132. The cubic root of 81293237 is about 433.1963669034.

It can be divided in two parts, 812 and 93237, that added together give a palindrome (94049).

The spelling of 81293237 in words is "eighty-one million, two hundred ninety-three thousand, two hundred thirty-seven".