21126102505961 has 4 divisors (see below), whose sum is σ = 21854588799300. Its totient is φ = 20397616212624.

The previous prime is 21126102505951. The next prime is 21126102506009. The reversal of 21126102505961 is 16950520162112.

It is a happy number.

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 17973148275625 + 3152954230336 = 4239475^2 + 1775656^2 .

It is a cyclic number.

It is not a de Polignac number, because 21126102505961 - 2²⁶ = 21126035397097 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21126102505951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 364243146626 + ... + 364243146683.

It is an arithmetic number, because the mean of its divisors is an integer number (5463647199825).

Almost surely, 2^{21126102505961} is an apocalyptic number.

It is an amenable number.

21126102505961 is a deficient number, since it is larger than the sum of its proper divisors (728486293339).

21126102505961 is an equidigital number, since it uses as much as digits as its factorization.

21126102505961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728486293338.

The product of its (nonzero) digits is 64800, while the sum is 41.

The spelling of 21126102505961 in words is "twenty-one trillion, one hundred twenty-six billion, one hundred two million, five hundred five thousand, nine hundred sixty-one".