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21111211021 = 154913628929
BaseRepresentation
bin10011101010010100…
…111000010000001101
32000111021110122012111
4103222110320100031
5321213432223041
613410502304021
71345104222115
oct235224702015
960437418174
1021111211021
118a5380133a
124112128011
131cb5982454
141043b02045
158385b8981
hex4ea53840d

21111211021 has 4 divisors (see below), whose sum is σ = 21124841500. Its totient is φ = 21097580544.

The previous prime is 21111211013. The next prime is 21111211109. The reversal of 21111211021 is 12011211112.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7681646025 + 13429564996 = 87645^2 + 115886^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111211021 - 23 = 21111211013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21111210992 and 21111211010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111211621) 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, 6812916 + ... + 6816013.

It is an arithmetic number, because the mean of its divisors is an integer number (5281210375).

Almost surely, 221111211021 is an apocalyptic number.

It is an amenable number.

21111211021 is a deficient number, since it is larger than the sum of its proper divisors (13630479).

21111211021 is a wasteful number, since it uses less digits than its factorization.

21111211021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13630478.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21111211021 its reverse (12011211112), we get a palindrome (33122422133).

Subtracting from 21111211021 its reverse (12011211112), we obtain a palindrome (9099999909).

The spelling of 21111211021 in words is "twenty-one billion, one hundred eleven million, two hundred eleven thousand, twenty-one".

Divisors: 1 1549 13628929 21111211021