21200111001 has 24 divisors (see below), whose sum is σ = 33300024264. Its totient is φ = 12942512640.

The previous prime is 21200110963. The next prime is 21200111003. The reversal of 21200111001 is 10011100212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 5550101001 + 15650010000 = 74499^2 + 125100^2 .

It is not a de Polignac number, because 21200111001 - 2¹⁰ = 21200109977 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21200111003) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1866810 + ... + 1878131.

It is an arithmetic number, because the mean of its divisors is an integer number (1387501011).

Almost surely, 2^21200111001 is an apocalyptic number.

It is an amenable number.

21200111001 is a deficient number, since it is larger than the sum of its proper divisors (12099913263).

21200111001 is a wasteful number, since it uses less digits than its factorization.

21200111001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3745001 (or 3744998 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21200111001 its reverse (10011100212), we get a palindrome (31211211213).

The spelling of 21200111001 in words is "twenty-one billion, two hundred million, one hundred eleven thousand, one".