81604447 has 2 divisors, whose sum is σ = 81604448. Its totient is φ = 81604446.

The previous prime is 81604427. The next prime is 81604543. The reversal of 81604447 is 74440618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81604447 - 2¹¹ = 81602399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81604427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40802223 + 40802224.

It is an arithmetic number, because the mean of its divisors is an integer number (40802224).

Almost surely, 2^81604447 is an apocalyptic number.

81604447 is a deficient number, since it is larger than the sum of its proper divisors (1).

81604447 is an equidigital number, since it uses as much as digits as its factorization.

81604447 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21504, while the sum is 34.

The square root of 81604447 is about 9033.5179747427. The cubic root of 81604447 is about 433.7484561730.

The spelling of 81604447 in words is "eighty-one million, six hundred four thousand, four hundred forty-seven".