21001200111 has 24 divisors (see below), whose sum is σ = 32509507680. Its totient is φ = 13030117056.

The previous prime is 21001200089. The next prime is 21001200119. The reversal of 21001200111 is 11100210012.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21001200111 is a prime.

It is a super-2 number, since 2×21001200111² (a number of 21 digits) contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 21001200093 and 21001200102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001200119) 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, 1363356 + ... + 1378673.

It is an arithmetic number, because the mean of its divisors is an integer number (1354562820).

Almost surely, 2^21001200111 is an apocalyptic number.

21001200111 is a deficient number, since it is larger than the sum of its proper divisors (11508307569).

21001200111 is a wasteful number, since it uses less digits than its factorization.

21001200111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2742095 (or 2742092 counting only the distinct ones).

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

Adding to 21001200111 its reverse (11100210012), we get a palindrome (32101410123).

Subtracting from 21001200111 its reverse (11100210012), we obtain a palindrome (9900990099).

The spelling of 21001200111 in words is "twenty-one billion, one million, two hundred thousand, one hundred eleven".