21540205101 has 16 divisors (see below), whose sum is σ = 28781708288. Its totient is φ = 14329450800.

The previous prime is 21540205091. The next prime is 21540205103. The reversal of 21540205101 is 10150204512.

It is not a de Polignac number, because 21540205101 - 2¹⁷ = 21540074029 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 (21540205103) by changing a digit.

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, 4166220 + ... + 4171386.

It is an arithmetic number, because the mean of its divisors is an integer number (1798856768).

Almost surely, 2^21540205101 is an apocalyptic number.

It is an amenable number.

21540205101 is a deficient number, since it is larger than the sum of its proper divisors (7241503187).

21540205101 is a wasteful number, since it uses less digits than its factorization.

21540205101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7872.

The product of its (nonzero) digits is 400, while the sum is 21.

Adding to 21540205101 its reverse (10150204512), we get a palindrome (31690409613).

The spelling of 21540205101 in words is "twenty-one billion, five hundred forty million, two hundred five thousand, one hundred one".