21110121001205 has 4 divisors (see below), whose sum is σ = 25332145201452. Its totient is φ = 16888096800960.

The previous prime is 21110121001153. The next prime is 21110121001241. The reversal of 21110121001205 is 50210012101112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15096752786116 + 6013368215089 = 3885454^2 + 2452217^2 .

It is not a de Polignac number, because 21110121001205 - 2⁶ = 21110121001141 is a prime.

It is a super-2 number, since 2×21110121001205² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2111012100116 + ... + 2111012100125.

It is an arithmetic number, because the mean of its divisors is an integer number (6333036300363).

Almost surely, 2^{21110121001205} is an apocalyptic number.

It is an amenable number.

21110121001205 is a deficient number, since it is larger than the sum of its proper divisors (4222024200247).

21110121001205 is an equidigital number, since it uses as much as digits as its factorization.

21110121001205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4222024200246.

The product of its (nonzero) digits is 40, while the sum is 17.

Adding to 21110121001205 its reverse (50210012101112), we get a palindrome (71320133102317).

The spelling of 21110121001205 in words is "twenty-one trillion, one hundred ten billion, one hundred twenty-one million, one thousand, two hundred five".