81182405 has 4 divisors (see below), whose sum is σ = 97418892. Its totient is φ = 64945920.

The previous prime is 81182377. The next prime is 81182411. The reversal of 81182405 is 50428118.

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 11142244 + 70040161 = 3338^2 + 8369^2 .

It is not a de Polignac number, because 81182405 - 2¹⁰ = 81181381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8118236 + ... + 8118245.

It is an arithmetic number, because the mean of its divisors is an integer number (24354723).

Almost surely, 2^81182405 is an apocalyptic number.

It is an amenable number.

81182405 is a deficient number, since it is larger than the sum of its proper divisors (16236487).

81182405 is a wasteful number, since it uses less digits than its factorization.

81182405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16236486.

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 81182405 is about 9010.1279125216. The cubic root of 81182405 is about 432.9994097423. Note that the first 3 decimals are identical.

The spelling of 81182405 in words is "eighty-one million, one hundred eighty-two thousand, four hundred five".