21653421105 has 16 divisors (see below), whose sum is σ = 35763070464. Its totient is φ = 11175959040.

The previous prime is 21653421103. The next prime is 21653421109. The reversal of 21653421105 is 50112435612.

It is not a de Polignac number, because 21653421105 - 2¹ = 21653421103 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21653421103) 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, 23282784 + ... + 23283713.

It is an arithmetic number, because the mean of its divisors is an integer number (2235191904).

Almost surely, 2^21653421105 is an apocalyptic number.

It is an amenable number.

21653421105 is a deficient number, since it is larger than the sum of its proper divisors (14109649359).

21653421105 is a wasteful number, since it uses less digits than its factorization.

21653421105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46566536.

The product of its (nonzero) digits is 7200, while the sum is 30.

Adding to 21653421105 its reverse (50112435612), we get a palindrome (71765856717).

The spelling of 21653421105 in words is "twenty-one billion, six hundred fifty-three million, four hundred twenty-one thousand, one hundred five".