21660135505 has 16 divisors (see below), whose sum is σ = 26368101504. Its totient is φ = 17077841280.

The previous prime is 21660135503. The next prime is 21660135551. The reversal of 21660135505 is 50553106612.

It is not a de Polignac number, because 21660135505 - 2¹ = 21660135503 is a prime.

It is a super-2 number, since 2×21660135505² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21660135503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 477250 + ... + 520660.

It is an arithmetic number, because the mean of its divisors is an integer number (1648006344).

Almost surely, 2^21660135505 is an apocalyptic number.

It is an amenable number.

21660135505 is a deficient number, since it is larger than the sum of its proper divisors (4707965999).

21660135505 is a wasteful number, since it uses less digits than its factorization.

21660135505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44856.

The product of its (nonzero) digits is 27000, while the sum is 34.

The spelling of 21660135505 in words is "twenty-one billion, six hundred sixty million, one hundred thirty-five thousand, five hundred five".