21138378989 has 8 divisors (see below), whose sum is σ = 26016466560. Its totient is φ = 16724871216.

The previous prime is 21138378917. The next prime is 21138379027. The reversal of 21138378989 is 98987383112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21138378989 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138378089) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 116144849 + ... + 116145030.

It is an arithmetic number, because the mean of its divisors is an integer number (3252058320).

Almost surely, 2^21138378989 is an apocalyptic number.

It is an amenable number.

21138378989 is a deficient number, since it is larger than the sum of its proper divisors (4878087571).

21138378989 is a wasteful number, since it uses less digits than its factorization.

21138378989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232289899.

The product of its digits is 5225472, while the sum is 59.

The spelling of 21138378989 in words is "twenty-one billion, one hundred thirty-eight million, three hundred seventy-eight thousand, nine hundred eighty-nine".