18920256691 has 16 divisors (see below), whose sum is σ = 22795591680. Its totient is φ = 15360294240.

The previous prime is 18920256689. The next prime is 18920256701. The reversal of 18920256691 is 19665202981.

It is a cyclic number.

It is not a de Polignac number, because 18920256691 - 2¹ = 18920256689 is a prime.

It is a super-2 number, since 2×18920256691² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18920256611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 917356 + ... + 937753.

It is an arithmetic number, because the mean of its divisors is an integer number (1424724480).

Almost surely, 2^18920256691 is an apocalyptic number.

18920256691 is a deficient number, since it is larger than the sum of its proper divisors (3875334989).

18920256691 is a wasteful number, since it uses less digits than its factorization.

18920256691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1855194.

The product of its (nonzero) digits is 466560, while the sum is 49.

The spelling of 18920256691 in words is "eighteen billion, nine hundred twenty million, two hundred fifty-six thousand, six hundred ninety-one".