81758381 has 2 divisors, whose sum is σ = 81758382. Its totient is φ = 81758380.

The previous prime is 81758359. The next prime is 81758401. The reversal of 81758381 is 18385718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59752900 + 22005481 = 7730^2 + 4691^2 .

It is a cyclic number.

It is not a de Polignac number, because 81758381 - 2⁶ = 81758317 is a prime.

It is a super-2 number, since 2×81758381² = 13368865727482322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81758581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40879190 + 40879191.

It is an arithmetic number, because the mean of its divisors is an integer number (40879191).

Almost surely, 2^81758381 is an apocalyptic number.

It is an amenable number.

81758381 is a deficient number, since it is larger than the sum of its proper divisors (1).

81758381 is an equidigital number, since it uses as much as digits as its factorization.

81758381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 53760, while the sum is 41.

The square root of 81758381 is about 9042.0341184935. The cubic root of 81758381 is about 434.0210176914.

The spelling of 81758381 in words is "eighty-one million, seven hundred fifty-eight thousand, three hundred eighty-one".