18405656957 has 4 divisors (see below), whose sum is σ = 18540004956. Its totient is φ = 18271308960.

The previous prime is 18405656923. The next prime is 18405656987. The reversal of 18405656957 is 75965650481.

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 15600259801 + 2805397156 = 124901^2 + 52966^2 .

It is a cyclic number.

It is not a de Polignac number, because 18405656957 - 2¹⁴ = 18405640573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18405656987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67173794 + ... + 67174067.

It is an arithmetic number, because the mean of its divisors is an integer number (4635001239).

Almost surely, 2^18405656957 is an apocalyptic number.

It is an amenable number.

18405656957 is a deficient number, since it is larger than the sum of its proper divisors (134347999).

18405656957 is a wasteful number, since it uses less digits than its factorization.

18405656957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134347998.

The product of its (nonzero) digits is 9072000, while the sum is 56.

The spelling of 18405656957 in words is "eighteen billion, four hundred five million, six hundred fifty-six thousand, nine hundred fifty-seven".