21146556026665 has 4 divisors (see below), whose sum is σ = 25375867232004. Its totient is φ = 16917244821328.

The previous prime is 21146556026653. The next prime is 21146556026699. The reversal of 21146556026665 is 56662065564112.

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 6963830154649 + 14182725872016 = 2638907^2 + 3765996^2 .

It is a cyclic number.

It is not a de Polignac number, because 21146556026665 - 2⁵ = 21146556026633 is a prime.

It is a Duffinian 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, 2114655602662 + ... + 2114655602671.

It is an arithmetic number, because the mean of its divisors is an integer number (6343966808001).

Almost surely, 2^{21146556026665} is an apocalyptic number.

It is an amenable number.

21146556026665 is a deficient number, since it is larger than the sum of its proper divisors (4229311205339).

21146556026665 is an equidigital number, since it uses as much as digits as its factorization.

21146556026665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4229311205338.

The product of its (nonzero) digits is 15552000, while the sum is 55.

The spelling of 21146556026665 in words is "twenty-one trillion, one hundred forty-six billion, five hundred fifty-six million, twenty-six thousand, six hundred sixty-five".