21203121101 has 4 divisors (see below), whose sum is σ = 21204800604. Its totient is φ = 21201441600.

The previous prime is 21203121061. The next prime is 21203121109. The reversal of 21203121101 is 10112130212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20477896201 + 725224900 = 143101^2 + 26930^2 .

It is a cyclic number.

It is not a de Polignac number, because 21203121101 - 2¹⁰ = 21203120077 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 (21203121109) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 820670 + ... + 846111.

It is an arithmetic number, because the mean of its divisors is an integer number (5301200151).

Almost surely, 2^21203121101 is an apocalyptic number.

It is an amenable number.

21203121101 is a deficient number, since it is larger than the sum of its proper divisors (1679503).

21203121101 is a wasteful number, since it uses less digits than its factorization.

21203121101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1679502.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21203121101 its reverse (10112130212), we get a palindrome (31315251313).

The spelling of 21203121101 in words is "twenty-one billion, two hundred three million, one hundred twenty-one thousand, one hundred one".