20819831138 has 4 divisors (see below), whose sum is σ = 31229746710. Its totient is φ = 10409915568.

The previous prime is 20819831113. The next prime is 20819831141. The reversal of 20819831138 is 83113891802.

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

It can be written as a sum of positive squares in only one way, i.e., 20139299569 + 680531569 = 141913^2 + 26087^2 .

It is a super-2 number, since 2×20819831138² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5204957783 + ... + 5204957786.

Almost surely, 2^20819831138 is an apocalyptic number.

20819831138 is a deficient number, since it is larger than the sum of its proper divisors (10409915572).

20819831138 is a wasteful number, since it uses less digits than its factorization.

20819831138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10409915571.

The product of its (nonzero) digits is 82944, while the sum is 44.

The spelling of 20819831138 in words is "twenty billion, eight hundred nineteen million, eight hundred thirty-one thousand, one hundred thirty-eight".