21905905238 has 8 divisors (see below), whose sum is σ = 37552980432. Its totient is φ = 9388245096.

The previous prime is 21905905213. The next prime is 21905905243. The reversal of 21905905238 is 83250950912.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 782353745 + ... + 782353772.

It is an arithmetic number, because the mean of its divisors is an integer number (4694122554).

Almost surely, 2^21905905238 is an apocalyptic number.

21905905238 is a deficient number, since it is larger than the sum of its proper divisors (15647075194).

21905905238 is a wasteful number, since it uses less digits than its factorization.

21905905238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1564707526.

The product of its (nonzero) digits is 194400, while the sum is 44.

The spelling of 21905905238 in words is "twenty-one billion, nine hundred five million, nine hundred five thousand, two hundred thirty-eight".