21001054565 has 8 divisors (see below), whose sum is σ = 25202239128. Its totient is φ = 16800194560.

The previous prime is 21001054517. The next prime is 21001054583. The reversal of 21001054565 is 56545010012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1637497156 + 19363557409 = 40466^2 + 139153^2 .

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

It is not a de Polignac number, because 21001054565 - 2²⁰ = 21000005989 is a prime.

It is a Duffinian number.

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 7 ways as a sum of consecutive naturals, for example, 96629 + ... + 226581.

It is an arithmetic number, because the mean of its divisors is an integer number (3150279891).

Almost surely, 2^21001054565 is an apocalyptic number.

It is an amenable number.

21001054565 is a deficient number, since it is larger than the sum of its proper divisors (4201184563).

21001054565 is a wasteful number, since it uses less digits than its factorization.

21001054565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162279.

The product of its (nonzero) digits is 6000, while the sum is 29.

Adding to 21001054565 its reverse (56545010012), we get a palindrome (77546064577).

The spelling of 21001054565 in words is "twenty-one billion, one million, fifty-four thousand, five hundred sixty-five".