21681258387 has 8 divisors (see below), whose sum is σ = 28915024320. Its totient is φ = 14450832360.

The previous prime is 21681258367. The next prime is 21681258419. The reversal of 21681258387 is 78385218612.

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

It is not a de Polignac number, because 21681258387 - 2⁶ = 21681258323 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21681258307) 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, 819789 + ... + 845822.

It is an arithmetic number, because the mean of its divisors is an integer number (3614378040).

Almost surely, 2^21681258387 is an apocalyptic number.

21681258387 is a deficient number, since it is larger than the sum of its proper divisors (7233765933).

21681258387 is a wasteful number, since it uses less digits than its factorization.

21681258387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1669953.

The product of its digits is 1290240, while the sum is 51.

The spelling of 21681258387 in words is "twenty-one billion, six hundred eighty-one million, two hundred fifty-eight thousand, three hundred eighty-seven".