21856906837 has 16 divisors (see below), whose sum is σ = 23063040000. Its totient is φ = 20691325872.

The previous prime is 21856906801. The next prime is 21856906867. The reversal of 21856906837 is 73860965812.

It is not a de Polignac number, because 21856906837 - 2¹⁹ = 21856382549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21856906867) 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 15 ways as a sum of consecutive naturals, for example, 155664 + ... + 260662.

It is an arithmetic number, because the mean of its divisors is an integer number (1441440000).

Almost surely, 2^21856906837 is an apocalyptic number.

It is an amenable number.

21856906837 is a deficient number, since it is larger than the sum of its proper divisors (1206133163).

21856906837 is a wasteful number, since it uses less digits than its factorization.

21856906837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105192.

The product of its (nonzero) digits is 4354560, while the sum is 55.

The spelling of 21856906837 in words is "twenty-one billion, eight hundred fifty-six million, nine hundred six thousand, eight hundred thirty-seven".