21521440005 has 32 divisors (see below), whose sum is σ = 37143797376. Its totient is φ = 10577827584.

The previous prime is 21521440001. The next prime is 21521440007. The reversal of 21521440005 is 50004412512.

It is not a de Polignac number, because 21521440005 - 2² = 21521440001 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521440001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 29514 + ... + 209556.

It is an arithmetic number, because the mean of its divisors is an integer number (1160743668).

Almost surely, 2^21521440005 is an apocalyptic number.

It is an amenable number.

21521440005 is a deficient number, since it is larger than the sum of its proper divisors (15622357371).

21521440005 is a wasteful number, since it uses less digits than its factorization.

21521440005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180677.

The product of its (nonzero) digits is 1600, while the sum is 24.

Adding to 21521440005 its reverse (50004412512), we get a palindrome (71525852517).

The spelling of 21521440005 in words is "twenty-one billion, five hundred twenty-one million, four hundred forty thousand, five".