21201111020105 has 16 divisors (see below), whose sum is σ = 25544295663120. Its totient is φ = 16892355551232.

The previous prime is 21201111020099. The next prime is 21201111020143. The reversal of 21201111020105 is 50102011110212.

It can be written as a sum of positive squares in 8 ways, for example, as 451956364729 + 20749154655376 = 672277^2 + 4555124^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201111020105 - 2³⁶ = 21132391543369 is a prime.

It is a super-2 number, since 2×21201111020105² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5206574 + ... + 8337303.

It is an arithmetic number, because the mean of its divisors is an integer number (1596518478945).

Almost surely, 2^{21201111020105} is an apocalyptic number.

It is an amenable number.

21201111020105 is a deficient number, since it is larger than the sum of its proper divisors (4343184643015).

21201111020105 is a wasteful number, since it uses less digits than its factorization.

21201111020105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13545148.

The product of its (nonzero) digits is 40, while the sum is 17.

Adding to 21201111020105 its reverse (50102011110212), we get a palindrome (71303122130317).

The spelling of 21201111020105 in words is "twenty-one trillion, two hundred one billion, one hundred eleven million, twenty thousand, one hundred five".