21564609100441 has 81 divisors (see below), whose sum is σ = 26594913231327. Its totient is φ = 17466522986880.

The previous prime is 21564609100429. The next prime is 21564609100453. The reversal of 21564609100441 is 14400190646512.

The square root of 21564609100441 is 4643771.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (21564609100429) and next prime (21564609100453).

It can be written as a sum of positive squares in only one way, i.e., 16789055528025 + 4775553572416 = 4097445^2 + 2185304^2 .

It is not a de Polignac number, because 21564609100441 - 2¹¹ = 21564609098393 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21564609103441) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 16499317710 + ... + 16499319016.

Almost surely, 2^{21564609100441} is an apocalyptic number.

21564609100441 is the 4643771-st square number.

21564609100441 is the 2321886-th centered octagonal number.

It is an amenable number.

21564609100441 is a deficient number, since it is larger than the sum of its proper divisors (5030304130886).

21564609100441 is an equidigital number, since it uses as much as digits as its factorization.

21564609100441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2708 (or 1354 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 43.

Adding to 21564609100441 its reverse (14400190646512), we get a palindrome (35964799746953).

The spelling of 21564609100441 in words is "twenty-one trillion, five hundred sixty-four billion, six hundred nine million, one hundred thousand, four hundred forty-one".