81755405 has 4 divisors (see below), whose sum is σ = 98106492. Its totient is φ = 65404320.

The previous prime is 81755357. The next prime is 81755413. The reversal of 81755405 is 50455718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 44129449 + 37625956 = 6643^2 + 6134^2 .

It is not a de Polignac number, because 81755405 - 2¹⁰ = 81754381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 8175536 + ... + 8175545.

It is an arithmetic number, because the mean of its divisors is an integer number (24526623).

Almost surely, 2^81755405 is an apocalyptic number.

It is an amenable number.

81755405 is a deficient number, since it is larger than the sum of its proper divisors (16351087).

81755405 is a wasteful number, since it uses less digits than its factorization.

81755405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16351086.

The product of its (nonzero) digits is 28000, while the sum is 35.

The square root of 81755405 is about 9041.8695522552. The cubic root of 81755405 is about 434.0157515148.

The spelling of 81755405 in words is "eighty-one million, seven hundred fifty-five thousand, four hundred five".