26561624021 has 2 divisors, whose sum is σ = 26561624022. Its totient is φ = 26561624020.

The previous prime is 26561623997. The next prime is 26561624069. The reversal of 26561624021 is 12042616562.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16406023396 + 10155600625 = 128086^2 + 100775^2 .

It is a cyclic number.

It is not a de Polignac number, because 26561624021 - 2¹⁸ = 26561361877 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (26561624071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13280812010 + 13280812011.

It is an arithmetic number, because the mean of its divisors is an integer number (13280812011).

Almost surely, 2^26561624021 is an apocalyptic number.

It is an amenable number.

26561624021 is a deficient number, since it is larger than the sum of its proper divisors (1).

26561624021 is an equidigital number, since it uses as much as digits as its factorization.

26561624021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 35.

The spelling of 26561624021 in words is "twenty-six billion, five hundred sixty-one million, six hundred twenty-four thousand, twenty-one".