21566341646 has 4 divisors (see below), whose sum is σ = 32349512472. Its totient is φ = 10783170822.

The previous prime is 21566341613. The next prime is 21566341649. The reversal of 21566341646 is 64614366512.

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

It is a junction number, because it is equal to n+sod(n) for n = 21566341597 and 21566341606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21566341649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5391585410 + ... + 5391585413.

It is an arithmetic number, because the mean of its divisors is an integer number (8087378118).

Almost surely, 2^21566341646 is an apocalyptic number.

21566341646 is a deficient number, since it is larger than the sum of its proper divisors (10783170826).

21566341646 is a wasteful number, since it uses less digits than its factorization.

21566341646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10783170825.

The product of its digits is 622080, while the sum is 44.

The spelling of 21566341646 in words is "twenty-one billion, five hundred sixty-six million, three hundred forty-one thousand, six hundred forty-six".