21043515253 has 16 divisors (see below), whose sum is σ = 21928206960. Its totient is φ = 20169676800.

The previous prime is 21043515217. The next prime is 21043515271. The reversal of 21043515253 is 35251534012.

It can be written as a sum of positive squares in 8 ways, for example, as 87478609 + 20956036644 = 9353^2 + 144762^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043515253 - 2²⁹ = 20506644341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21043518253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9473683 + ... + 9475903.

It is an arithmetic number, because the mean of its divisors is an integer number (1370512935).

Almost surely, 2^21043515253 is an apocalyptic number.

It is an amenable number.

21043515253 is a deficient number, since it is larger than the sum of its proper divisors (884691707).

21043515253 is a wasteful number, since it uses less digits than its factorization.

21043515253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4488.

The product of its (nonzero) digits is 18000, while the sum is 31.

The spelling of 21043515253 in words is "twenty-one billion, forty-three million, five hundred fifteen thousand, two hundred fifty-three".