81837257 has 2 divisors, whose sum is σ = 81837258. Its totient is φ = 81837256.

The previous prime is 81837233. The next prime is 81837277. The reversal of 81837257 is 75273818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64705936 + 17131321 = 8044^2 + 4139^2 .

It is a cyclic number.

It is not a de Polignac number, because 81837257 - 2⁶ = 81837193 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81837277) 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, 40918628 + 40918629.

It is an arithmetic number, because the mean of its divisors is an integer number (40918629).

Almost surely, 2^81837257 is an apocalyptic number.

It is an amenable number.

81837257 is a deficient number, since it is larger than the sum of its proper divisors (1).

81837257 is an equidigital number, since it uses as much as digits as its factorization.

81837257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 94080, while the sum is 41.

The square root of 81837257 is about 9046.3946962312. The cubic root of 81837257 is about 434.1605460525.

The spelling of 81837257 in words is "eighty-one million, eight hundred thirty-seven thousand, two hundred fifty-seven".