21920646438601 has 9 divisors (see below), whose sum is σ = 22915268488749. Its totient is φ = 20967471851436.

The previous prime is 21920646438599. The next prime is 21920646438641. The reversal of 21920646438601 is 10683464602912.

The square root of 21920646438601 is 4681949.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21920646438601 - 2¹ = 21920646438599 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21920646438641) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 107583046 + ... + 107786608.

Almost surely, 2^{21920646438601} is an apocalyptic number.

21920646438601 is the 4681949-th square number.

21920646438601 is the 2340975-th centered octagonal number.

It is an amenable number.

21920646438601 is a deficient number, since it is larger than the sum of its proper divisors (994622050148).

21920646438601 is an frugal number, since it uses more digits than its factorization.

21920646438601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407172 (or 203586 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 52.

The spelling of 21920646438601 in words is "twenty-one trillion, nine hundred twenty billion, six hundred forty-six million, four hundred thirty-eight thousand, six hundred one".