21121100001 has 96 divisors (see below), whose sum is σ = 33066633600. Its totient is φ = 13464921600.

The previous prime is 21121099991. The next prime is 21121100047. The reversal of 21121100001 is 10000112112.

It is a happy number.

It is not a de Polignac number, because 21121100001 - 2¹¹ = 21121097953 is a prime.

It is a super-2 number, since 2×21121100001² (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 not an unprimeable number, because it can be changed into a prime (21121100071) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 141752275 + ... + 141752423.

It is an arithmetic number, because the mean of its divisors is an integer number (344444100).

Almost surely, 2^21121100001 is an apocalyptic number.

It is an amenable number.

21121100001 is a deficient number, since it is larger than the sum of its proper divisors (11945533599).

21121100001 is a wasteful number, since it uses less digits than its factorization.

21121100001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 429 (or 417 counting only the distinct ones).

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

Adding to 21121100001 its reverse (10000112112), we get a palindrome (31121212113).

The spelling of 21121100001 in words is "twenty-one billion, one hundred twenty-one million, one hundred thousand, one".