21905071065 has 48 divisors (see below), whose sum is σ = 38119423680. Its totient is φ = 11636472960.

The previous prime is 21905071037. The next prime is 21905071087. The reversal of 21905071065 is 56017050912.

21905071065 is a `hidden beast` number, since 2 + 1 + 90 + 507 + 1 + 0 + 65 = 666.

It is not a de Polignac number, because 21905071065 - 2⁹ = 21905070553 is a prime.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 21496126 + ... + 21497144.

It is an arithmetic number, because the mean of its divisors is an integer number (794154660).

Almost surely, 2^21905071065 is an apocalyptic number.

It is an amenable number.

21905071065 is a deficient number, since it is larger than the sum of its proper divisors (16214352615).

21905071065 is a wasteful number, since it uses less digits than its factorization.

21905071065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2454 (or 2451 counting only the distinct ones).

The product of its (nonzero) digits is 18900, while the sum is 36.

The spelling of 21905071065 in words is "twenty-one billion, nine hundred five million, seventy-one thousand, sixty-five".