21012535505 has 16 divisors (see below), whose sum is σ = 27888574224. Its totient is φ = 15097570560.

The previous prime is 21012535493. The next prime is 21012535529. The reversal of 21012535505 is 50553521012.

It can be written as a sum of positive squares in 8 ways, for example, as 1419254929 + 19593280576 = 37673^2 + 139976^2 .

It is not a de Polignac number, because 21012535505 - 2⁶ = 21012535441 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4366106 + ... + 4370915.

It is an arithmetic number, because the mean of its divisors is an integer number (1743035889).

Almost surely, 2^21012535505 is an apocalyptic number.

It is an amenable number.

21012535505 is a deficient number, since it is larger than the sum of its proper divisors (6876038719).

21012535505 is a wasteful number, since it uses less digits than its factorization.

21012535505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8737076.

The product of its (nonzero) digits is 7500, while the sum is 29.

The spelling of 21012535505 in words is "twenty-one billion, twelve million, five hundred thirty-five thousand, five hundred five".