81929461 has 2 divisors, whose sum is σ = 81929462. Its totient is φ = 81929460.

The previous prime is 81929459. The next prime is 81929489. The reversal of 81929461 is 16492918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42315025 + 39614436 = 6505^2 + 6294^2 .

It is a cyclic number.

It is not a de Polignac number, because 81929461 - 2¹ = 81929459 is a prime.

Together with 81929459, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81929411) 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, 40964730 + 40964731.

It is an arithmetic number, because the mean of its divisors is an integer number (40964731).

Almost surely, 2^81929461 is an apocalyptic number.

It is an amenable number.

81929461 is a deficient number, since it is larger than the sum of its proper divisors (1).

81929461 is an equidigital number, since it uses as much as digits as its factorization.

81929461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 40.

The square root of 81929461 is about 9051.4894354465. The cubic root of 81929461 is about 434.3235374810.

The spelling of 81929461 in words is "eighty-one million, nine hundred twenty-nine thousand, four hundred sixty-one".