21608378660801 has 2 divisors, whose sum is σ = 21608378660802. Its totient is φ = 21608378660800.

The previous prime is 21608378660797. The next prime is 21608378660819. The reversal of 21608378660801 is 10806687380612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19413047488576 + 2195331172225 = 4406024^2 + 1481665^2 .

It is a cyclic number.

It is not a de Polignac number, because 21608378660801 - 2² = 21608378660797 is a prime.

It is not a weakly prime, because it can be changed into another prime (21608378660821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10804189330400 + 10804189330401.

It is an arithmetic number, because the mean of its divisors is an integer number (10804189330401).

Almost surely, 2^{21608378660801} is an apocalyptic number.

It is an amenable number.

21608378660801 is a deficient number, since it is larger than the sum of its proper divisors (1).

21608378660801 is an equidigital number, since it uses as much as digits as its factorization.

21608378660801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4644864, while the sum is 56.

The spelling of 21608378660801 in words is "twenty-one trillion, six hundred eight billion, three hundred seventy-eight million, six hundred sixty thousand, eight hundred one".