21000021212111 has 4 divisors (see below), whose sum is σ = 21002512621800. Its totient is φ = 20997529802424.

The previous prime is 21000021212101. The next prime is 21000021212143. The reversal of 21000021212111 is 11121212000012.

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

It is a cyclic number.

It is not a de Polignac number, because 21000021212111 - 2⁴² = 16601974701007 is a prime.

It is a super-2 number, since 2×21000021212111² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000021212101) 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, 1245692201 + ... + 1245709058.

It is an arithmetic number, because the mean of its divisors is an integer number (5250628155450).

Almost surely, 2^{21000021212111} is an apocalyptic number.

21000021212111 is a deficient number, since it is larger than the sum of its proper divisors (2491409689).

21000021212111 is an equidigital number, since it uses as much as digits as its factorization.

21000021212111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2491409688.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21000021212111 its reverse (11121212000012), we get a palindrome (32121233212123).

The spelling of 21000021212111 in words is "twenty-one trillion, twenty-one million, two hundred twelve thousand, one hundred eleven".