20318731891 has 8 divisors (see below), whose sum is σ = 21574903824. Its totient is φ = 19069332480.

The previous prime is 20318731877. The next prime is 20318731903. The reversal of 20318731891 is 19813781302.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20318731891 - 2²¹ = 20316634739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20318731871) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1686945 + ... + 1698946.

It is an arithmetic number, because the mean of its divisors is an integer number (2696862978).

Almost surely, 2^20318731891 is an apocalyptic number.

20318731891 is a deficient number, since it is larger than the sum of its proper divisors (1256171933).

20318731891 is a wasteful number, since it uses less digits than its factorization.

20318731891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3386261.

The product of its (nonzero) digits is 72576, while the sum is 43.

The spelling of 20318731891 in words is "twenty billion, three hundred eighteen million, seven hundred thirty-one thousand, eight hundred ninety-one".