81845537 has 2 divisors, whose sum is σ = 81845538. Its totient is φ = 81845536.

The previous prime is 81845509. The next prime is 81845539. The reversal of 81845537 is 73554818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72658576 + 9186961 = 8524^2 + 3031^2 .

It is a cyclic number.

It is not a de Polignac number, because 81845537 - 2²⁴ = 65068321 is a prime.

Together with 81845539, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81845494 and 81845503.

It is not a weakly prime, because it can be changed into another prime (81845539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40922768 + 40922769.

It is an arithmetic number, because the mean of its divisors is an integer number (40922769).

Almost surely, 2^81845537 is an apocalyptic number.

It is an amenable number.

81845537 is a deficient number, since it is larger than the sum of its proper divisors (1).

81845537 is an equidigital number, since it uses as much as digits as its factorization.

81845537 is an evil number, because the sum of its binary digits is even.

The product of its digits is 134400, while the sum is 41.

The square root of 81845537 is about 9046.8523255329. The cubic root of 81845537 is about 434.1751878274.

The spelling of 81845537 in words is "eighty-one million, eight hundred forty-five thousand, five hundred thirty-seven".