21655214364661 has 4 divisors (see below), whose sum is σ = 21735122905024. Its totient is φ = 21575305824300.

The previous prime is 21655214364611. The next prime is 21655214364709. The reversal of 21655214364661 is 16646341255612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21655214364661 - 2⁷ = 21655214364533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21655214364599 and 21655214364608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21655214364611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39954269775 + ... + 39954270316.

It is an arithmetic number, because the mean of its divisors is an integer number (5433780726256).

Almost surely, 2^{21655214364661} is an apocalyptic number.

It is an amenable number.

21655214364661 is a deficient number, since it is larger than the sum of its proper divisors (79908540363).

21655214364661 is an equidigital number, since it uses as much as digits as its factorization.

21655214364661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79908540362.

The product of its digits is 6220800, while the sum is 52.

The spelling of 21655214364661 in words is "twenty-one trillion, six hundred fifty-five billion, two hundred fourteen million, three hundred sixty-four thousand, six hundred sixty-one".