81490729 has 2 divisors, whose sum is σ = 81490730. Its totient is φ = 81490728.

The previous prime is 81490697. The next prime is 81490757. The reversal of 81490729 is 92709418.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78801129 + 2689600 = 8877^2 + 1640^2 .

It is a cyclic number.

It is not a de Polignac number, because 81490729 - 2⁵ = 81490697 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 81490691 and 81490700.

It is not a weakly prime, because it can be changed into another prime (81490769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40745364 + 40745365.

It is an arithmetic number, because the mean of its divisors is an integer number (40745365).

Almost surely, 2^81490729 is an apocalyptic number.

It is an amenable number.

81490729 is a deficient number, since it is larger than the sum of its proper divisors (1).

81490729 is an equidigital number, since it uses as much as digits as its factorization.

81490729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 81490729 is about 9027.2215548307. The cubic root of 81490729 is about 433.5468824500.

The spelling of 81490729 in words is "eighty-one million, four hundred ninety thousand, seven hundred twenty-nine".