21568920505 has 16 divisors (see below), whose sum is σ = 28293219648. Its totient is φ = 15654520000.

The previous prime is 21568920487. The next prime is 21568920509. The reversal of 21568920505 is 50502986512.

It is not a de Polignac number, because 21568920505 - 2²¹ = 21566823353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21568920509) 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, 372346 + ... + 426355.

It is an arithmetic number, because the mean of its divisors is an integer number (1768326228).

Almost surely, 2^21568920505 is an apocalyptic number.

It is an amenable number.

21568920505 is a deficient number, since it is larger than the sum of its proper divisors (6724299143).

21568920505 is a wasteful number, since it uses less digits than its factorization.

21568920505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 799208.

The product of its (nonzero) digits is 216000, while the sum is 43.

The spelling of 21568920505 in words is "twenty-one billion, five hundred sixty-eight million, nine hundred twenty thousand, five hundred five".