20687658138 has 48 divisors (see below), whose sum is σ = 52993025280. Its totient is φ = 5706939168.

The previous prime is 20687658137. The next prime is 20687658143. The reversal of 20687658138 is 83185678602.

20687658138 is a `hidden beast` number, since 20 + 6 + 8 + 7 + 6 + 581 + 38 = 666.

It is not an unprimeable number, because it can be changed into a prime (20687658137) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2827170 + ... + 2834477.

It is an arithmetic number, because the mean of its divisors is an integer number (1104021360).

Almost surely, 2^20687658138 is an apocalyptic number.

20687658138 is an abundant number, since it is smaller than the sum of its proper divisors (32305367142).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20687658138 is a wasteful number, since it uses less digits than its factorization.

20687658138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5661691 (or 5661688 counting only the distinct ones).

The product of its (nonzero) digits is 3870720, while the sum is 54.

The spelling of 20687658138 in words is "twenty billion, six hundred eighty-seven million, six hundred fifty-eight thousand, one hundred thirty-eight".