21640543055 has 4 divisors (see below), whose sum is σ = 25968651672. Its totient is φ = 17312434440.

The previous prime is 21640543039. The next prime is 21640543063. The reversal of 21640543055 is 55034504612.

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

It is not a de Polignac number, because 21640543055 - 2⁴ = 21640543039 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, 2164054301 + ... + 2164054310.

It is an arithmetic number, because the mean of its divisors is an integer number (6492162918).

Almost surely, 2^21640543055 is an apocalyptic number.

21640543055 is a deficient number, since it is larger than the sum of its proper divisors (4328108617).

21640543055 is an equidigital number, since it uses as much as digits as its factorization.

21640543055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4328108616.

The product of its (nonzero) digits is 72000, while the sum is 35.

The spelling of 21640543055 in words is "twenty-one billion, six hundred forty million, five hundred forty-three thousand, fifty-five".