81787049 has 2 divisors, whose sum is σ = 81787050. Its totient is φ = 81787048.

The previous prime is 81787033. The next prime is 81787093. The reversal of 81787049 is 94078718.

It is an a-pointer prime, because the next prime (81787093) can be obtained adding 81787049 to its sum of digits (44).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 47059600 + 34727449 = 6860^2 + 5893^2 .

It is a cyclic number.

It is not a de Polignac number, because 81787049 - 2⁴ = 81787033 is a prime.

It is not a weakly prime, because it can be changed into another prime (81787009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40893524 + 40893525.

It is an arithmetic number, because the mean of its divisors is an integer number (40893525).

Almost surely, 2^81787049 is an apocalyptic number.

It is an amenable number.

81787049 is a deficient number, since it is larger than the sum of its proper divisors (1).

81787049 is an equidigital number, since it uses as much as digits as its factorization.

81787049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 112896, while the sum is 44.

The square root of 81787049 is about 9043.6192423167. The cubic root of 81787049 is about 434.0717405668.

The spelling of 81787049 in words is "eighty-one million, seven hundred eighty-seven thousand, forty-nine".