81659429 has 2 divisors, whose sum is σ = 81659430. Its totient is φ = 81659428.

The previous prime is 81659411. The next prime is 81659471. The reversal of 81659429 is 92495618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78676900 + 2982529 = 8870^2 + 1727^2 .

It is a cyclic number.

It is not a de Polignac number, because 81659429 - 2⁸ = 81659173 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81659429.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81659029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40829714 + 40829715.

It is an arithmetic number, because the mean of its divisors is an integer number (40829715).

Almost surely, 2^81659429 is an apocalyptic number.

It is an amenable number.

81659429 is a deficient number, since it is larger than the sum of its proper divisors (1).

81659429 is an equidigital number, since it uses as much as digits as its factorization.

81659429 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 44.

The square root of 81659429 is about 9036.5606842427. The cubic root of 81659429 is about 433.8458487558.

The spelling of 81659429 in words is "eighty-one million, six hundred fifty-nine thousand, four hundred twenty-nine".