81129751 has 2 divisors, whose sum is σ = 81129752. Its totient is φ = 81129750.

The previous prime is 81129731. The next prime is 81129757. The reversal of 81129751 is 15792118.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81129751 - 2⁷ = 81129623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81129757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40564875 + 40564876.

It is an arithmetic number, because the mean of its divisors is an integer number (40564876).

Almost surely, 2^81129751 is an apocalyptic number.

81129751 is a deficient number, since it is larger than the sum of its proper divisors (1).

81129751 is an equidigital number, since it uses as much as digits as its factorization.

81129751 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 34.

The square root of 81129751 is about 9007.2055044836. The cubic root of 81129751 is about 432.9057766380.

The spelling of 81129751 in words is "eighty-one million, one hundred twenty-nine thousand, seven hundred fifty-one".