21666124653 has 4 divisors (see below), whose sum is σ = 28888166208. Its totient is φ = 14444083100.

The previous prime is 21666124639. The next prime is 21666124673. The reversal of 21666124653 is 35642166612.

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 21666124653 - 2⁵ = 21666124621 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666124603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3611020773 + ... + 3611020778.

It is an arithmetic number, because the mean of its divisors is an integer number (7222041552).

Almost surely, 2^21666124653 is an apocalyptic number.

It is an amenable number.

21666124653 is a deficient number, since it is larger than the sum of its proper divisors (7222041555).

21666124653 is an equidigital number, since it uses as much as digits as its factorization.

21666124653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7222041554.

The product of its digits is 311040, while the sum is 42.

The spelling of 21666124653 in words is "twenty-one billion, six hundred sixty-six million, one hundred twenty-four thousand, six hundred fifty-three".