21126530861 has 2 divisors, whose sum is σ = 21126530862. Its totient is φ = 21126530860.

The previous prime is 21126530857. The next prime is 21126530869. The reversal of 21126530861 is 16803562112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18273902761 + 2852628100 = 135181^2 + 53410^2 .

It is a cyclic number.

It is not a de Polignac number, because 21126530861 - 2² = 21126530857 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21126530869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10563265430 + 10563265431.

It is an arithmetic number, because the mean of its divisors is an integer number (10563265431).

Almost surely, 2^21126530861 is an apocalyptic number.

It is an amenable number.

21126530861 is a deficient number, since it is larger than the sum of its proper divisors (1).

21126530861 is an equidigital number, since it uses as much as digits as its factorization.

21126530861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 35.

The spelling of 21126530861 in words is "twenty-one billion, one hundred twenty-six million, five hundred thirty thousand, eight hundred sixty-one".