21366561023 has 8 divisors (see below), whose sum is σ = 21390272400. Its totient is φ = 21342866688.

The previous prime is 21366561019. The next prime is 21366561049. The reversal of 21366561023 is 32016566312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21366561023 - 2² = 21366561019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366561523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6428240 + ... + 6431562.

It is an arithmetic number, because the mean of its divisors is an integer number (2673784050).

Almost surely, 2^21366561023 is an apocalyptic number.

21366561023 is a deficient number, since it is larger than the sum of its proper divisors (23711377).

21366561023 is a wasteful number, since it uses less digits than its factorization.

21366561023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8521.

The product of its (nonzero) digits is 38880, while the sum is 35.

The spelling of 21366561023 in words is "twenty-one billion, three hundred sixty-six million, five hundred sixty-one thousand, twenty-three".