21001121100021 has 32 divisors (see below), whose sum is σ = 29784222437760. Its totient is φ = 13124878626816.

The previous prime is 21001121099999. The next prime is 21001121100077. The reversal of 21001121100021 is 12000112110012.

It is not a de Polignac number, because 21001121100021 - 2¹⁸ = 21001120837877 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001121100221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32282455 + ... + 32926571.

It is an arithmetic number, because the mean of its divisors is an integer number (930756951180).

Almost surely, 2^{21001121100021} is an apocalyptic number.

It is an amenable number.

21001121100021 is a deficient number, since it is larger than the sum of its proper divisors (8783101337739).

21001121100021 is a wasteful number, since it uses less digits than its factorization.

21001121100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 650133.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21001121100021 its reverse (12000112110012), we get a palindrome (33001233210033).

The spelling of 21001121100021 in words is "twenty-one trillion, one billion, one hundred twenty-one million, one hundred thousand, twenty-one".