21581545585 has 8 divisors (see below), whose sum is σ = 25921598976. Its totient is φ = 17249406960.

The previous prime is 21581545567. The next prime is 21581545591. The reversal of 21581545585 is 58554518512.

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

It is not a de Polignac number, because 21581545585 - 2²¹ = 21579448433 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1972689 + ... + 1983598.

It is an arithmetic number, because the mean of its divisors is an integer number (3240199872).

Almost surely, 2^21581545585 is an apocalyptic number.

It is an amenable number.

21581545585 is a deficient number, since it is larger than the sum of its proper divisors (4340053391).

21581545585 is a wasteful number, since it uses less digits than its factorization.

21581545585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3957383.

The product of its digits is 1600000, while the sum is 49.

The spelling of 21581545585 in words is "twenty-one billion, five hundred eighty-one million, five hundred forty-five thousand, five hundred eighty-five".