21105839387 has 4 divisors (see below), whose sum is σ = 21451836816. Its totient is φ = 20759841960.

The previous prime is 21105839383. The next prime is 21105839389. The reversal of 21105839387 is 78393850112.

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

It is a cyclic number.

It is not a de Polignac number, because 21105839387 - 2² = 21105839383 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21105839383) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 172998623 + ... + 172998744.

It is an arithmetic number, because the mean of its divisors is an integer number (5362959204).

Almost surely, 2^21105839387 is an apocalyptic number.

21105839387 is a deficient number, since it is larger than the sum of its proper divisors (345997429).

21105839387 is an equidigital number, since it uses as much as digits as its factorization.

21105839387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345997428.

The product of its (nonzero) digits is 362880, while the sum is 47.

The spelling of 21105839387 in words is "twenty-one billion, one hundred five million, eight hundred thirty-nine thousand, three hundred eighty-seven".