21720023201 has 2 divisors, whose sum is σ = 21720023202. Its totient is φ = 21720023200.

The previous prime is 21720023189. The next prime is 21720023231. The reversal of 21720023201 is 10232002712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21585486400 + 134536801 = 146920^2 + 11599^2 .

It is a cyclic number.

It is not a de Polignac number, because 21720023201 - 2¹⁴ = 21720006817 is a prime.

It is not a weakly prime, because it can be changed into another prime (21720023231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10860011600 + 10860011601.

It is an arithmetic number, because the mean of its divisors is an integer number (10860011601).

Almost surely, 2^21720023201 is an apocalyptic number.

It is an amenable number.

21720023201 is a deficient number, since it is larger than the sum of its proper divisors (1).

21720023201 is an equidigital number, since it uses as much as digits as its factorization.

21720023201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 20.

Adding to 21720023201 its reverse (10232002712), we get a palindrome (31952025913).

The spelling of 21720023201 in words is "twenty-one billion, seven hundred twenty million, twenty-three thousand, two hundred one".