21546566513 has 8 divisors (see below), whose sum is σ = 22932222408. Its totient is φ = 20174045184.

The previous prime is 21546566507. The next prime is 21546566539. The reversal of 21546566513 is 31566564512.

It can be written as a sum of positive squares in 4 ways, for example, as 2049191824 + 19497374689 = 45268^2 + 139633^2 .

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 21546566513 - 2¹⁸ = 21546304369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21546560513) 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 in 7 ways as a sum of consecutive naturals, for example, 3280256 + ... + 3286817.

It is an arithmetic number, because the mean of its divisors is an integer number (2866527801).

Almost surely, 2^21546566513 is an apocalyptic number.

It is an amenable number.

21546566513 is a deficient number, since it is larger than the sum of its proper divisors (1385655895).

21546566513 is a wasteful number, since it uses less digits than its factorization.

21546566513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6567283.

The product of its digits is 648000, while the sum is 44.

The spelling of 21546566513 in words is "twenty-one billion, five hundred forty-six million, five hundred sixty-six thousand, five hundred thirteen".