21040709138 has 8 divisors (see below), whose sum is σ = 32078458380. Its totient is φ = 10347889680.

The previous prime is 21040709113. The next prime is 21040709147. The reversal of 21040709138 is 83190704012.

21040709138 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 21020070289 + 20638849 = 144983^2 + 4543^2 .

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

It is a super-2 number, since 2×21040709138² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21040709098 and 21040709107.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 86232293 + ... + 86232536.

Almost surely, 2^21040709138 is an apocalyptic number.

21040709138 is a deficient number, since it is larger than the sum of its proper divisors (11037749242).

21040709138 is a wasteful number, since it uses less digits than its factorization.

21040709138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172464892.

The product of its (nonzero) digits is 12096, while the sum is 35.

The spelling of 21040709138 in words is "twenty-one billion, forty million, seven hundred nine thousand, one hundred thirty-eight".