21176381538 has 24 divisors (see below), whose sum is σ = 49411557468. Its totient is φ = 6515809632.

The previous prime is 21176381531. The next prime is 21176381609. The reversal of 21176381538 is 83518367112.

It is a happy number.

21176381538 is a `hidden beast` number, since 2 + 1 + 1 + 7 + 638 + 1 + 5 + 3 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 20960379729 + 216001809 = 144777^2 + 14697^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21176381493 and 21176381502.

It is not an unprimeable number, because it can be changed into a prime (21176381531) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 45248445 + ... + 45248912.

Almost surely, 2^21176381538 is an apocalyptic number.

21176381538 is an abundant number, since it is smaller than the sum of its proper divisors (28235175930).

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

21176381538 is a wasteful number, since it uses less digits than its factorization.

21176381538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90497378 (or 90497375 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The spelling of 21176381538 in words is "twenty-one billion, one hundred seventy-six million, three hundred eighty-one thousand, five hundred thirty-eight".