21152666436641 has 4 divisors (see below), whose sum is σ = 22396940932932. Its totient is φ = 19908391940352.

The previous prime is 21152666436599. The next prime is 21152666436661. The reversal of 21152666436641 is 14663466625112.

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 19124047341025 + 2028619095616 = 4373105^2 + 1424296^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21152666436641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21152666436661) 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, 622137248120 + ... + 622137248153.

It is an arithmetic number, because the mean of its divisors is an integer number (5599235233233).

Almost surely, 2^{21152666436641} is an apocalyptic number.

It is an amenable number.

21152666436641 is a deficient number, since it is larger than the sum of its proper divisors (1244274496291).

21152666436641 is a wasteful number, since it uses less digits than its factorization.

21152666436641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244274496290.

The product of its digits is 7464960, while the sum is 53.

The spelling of 21152666436641 in words is "twenty-one trillion, one hundred fifty-two billion, six hundred sixty-six million, four hundred thirty-six thousand, six hundred forty-one".