21542720005 has 4 divisors (see below), whose sum is σ = 25851264012. Its totient is φ = 17234176000.

The previous prime is 21542719999. The next prime is 21542720047. The reversal of 21542720005 is 50002724512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3186263809 + 18356456196 = 56447^2 + 135486^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21542720005 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2154271996 + ... + 2154272005.

It is an arithmetic number, because the mean of its divisors is an integer number (6462816003).

Almost surely, 2^21542720005 is an apocalyptic number.

It is an amenable number.

21542720005 is a deficient number, since it is larger than the sum of its proper divisors (4308544007).

21542720005 is an equidigital number, since it uses as much as digits as its factorization.

21542720005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4308544006.

The product of its (nonzero) digits is 5600, while the sum is 28.

The spelling of 21542720005 in words is "twenty-one billion, five hundred forty-two million, seven hundred twenty thousand, five".