21216210631601 has 2 divisors, whose sum is σ = 21216210631602. Its totient is φ = 21216210631600.

The previous prime is 21216210631543. The next prime is 21216210631613. The reversal of 21216210631601 is 10613601261212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20742695992225 + 473514639376 = 4554415^2 + 688124^2 .

It is a cyclic number.

It is not a de Polignac number, because 21216210631601 - 2⁴² = 16818164120497 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21216210631001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608105315800 + 10608105315801.

It is an arithmetic number, because the mean of its divisors is an integer number (10608105315801).

Almost surely, 2^{21216210631601} is an apocalyptic number.

It is an amenable number.

21216210631601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216210631601 is an equidigital number, since it uses as much as digits as its factorization.

21216210631601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 32.

Adding to 21216210631601 its reverse (10613601261212), we get a palindrome (31829811892813).

The spelling of 21216210631601 in words is "twenty-one trillion, two hundred sixteen billion, two hundred ten million, six hundred thirty-one thousand, six hundred one".