21105505707 has 48 divisors (see below), whose sum is σ = 33343057440. Its totient is φ = 11795857920.

The previous prime is 21105505699. The next prime is 21105505721. The reversal of 21105505707 is 70750550112.

It is not a de Polignac number, because 21105505707 - 2³ = 21105505699 is a prime.

It is a super-2 number, since 2×21105505707² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21105505727) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8063463 + ... + 8066079.

It is an arithmetic number, because the mean of its divisors is an integer number (694647030).

Almost surely, 2^21105505707 is an apocalyptic number.

21105505707 is a deficient number, since it is larger than the sum of its proper divisors (12237551733).

21105505707 is a wasteful number, since it uses less digits than its factorization.

21105505707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4364 (or 4353 counting only the distinct ones).

The product of its (nonzero) digits is 12250, while the sum is 33.

The spelling of 21105505707 in words is "twenty-one billion, one hundred five million, five hundred five thousand, seven hundred seven".