21001200111173 has 2 divisors, whose sum is σ = 21001200111174. Its totient is φ = 21001200111172.

The previous prime is 21001200111107. The next prime is 21001200111187. The reversal of 21001200111173 is 37111100210012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14971312241284 + 6029887869889 = 3869278^2 + 2455583^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001200111173 - 2³⁰ = 21000126369349 is a prime.

It is a super-2 number, since 2×21001200111173² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001200161173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500600055586 + 10500600055587.

It is an arithmetic number, because the mean of its divisors is an integer number (10500600055587).

Almost surely, 2^{21001200111173} is an apocalyptic number.

It is an amenable number.

21001200111173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001200111173 is an equidigital number, since it uses as much as digits as its factorization.

21001200111173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 20.

Adding to 21001200111173 its reverse (37111100210012), we get a palindrome (58112300321185).

The spelling of 21001200111173 in words is "twenty-one trillion, one billion, two hundred million, one hundred eleven thousand, one hundred seventy-three".