21154520613601 has 2 divisors, whose sum is σ = 21154520613602. Its totient is φ = 21154520613600.

The previous prime is 21154520613587. The next prime is 21154520613617. The reversal of 21154520613601 is 10631602545112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16548135843600 + 4606384770001 = 4067940^2 + 2146249^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154520613601 - 2⁹ = 21154520613089 is a prime.

It is not a weakly prime, because it can be changed into another prime (21154520613631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577260306800 + 10577260306801.

It is an arithmetic number, because the mean of its divisors is an integer number (10577260306801).

Almost surely, 2^{21154520613601} is an apocalyptic number.

It is an amenable number.

21154520613601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154520613601 is an equidigital number, since it uses as much as digits as its factorization.

21154520613601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21154520613601 in words is "twenty-one trillion, one hundred fifty-four billion, five hundred twenty million, six hundred thirteen thousand, six hundred one".