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21211212100 = 22521316316317
BaseRepresentation
bin10011110000010010…
…010110100101000100
32000202020122012220011
4103300102112211010
5321420032241400
613424433520004
71350430220341
oct236022264504
960666565804
1021211212100
118aa51a3661
12413b713004
1320005c65a0
1410530d37c8
1584226d8ba
hex4f0496944

21211212100 has 36 divisors (see below), whose sum is σ = 49568974084. Its totient is φ = 7831831680.

The previous prime is 21211212083. The next prime is 21211212107. The reversal of 21211212100 is 121211212.

It can be written as a sum of positive squares in 6 ways, for example, as 5524651584 + 15686560516 = 74328^2 + 125246^2 .

It is a Harshad number since it is a multiple of its sum of digits (13).

It is not an unprimeable number, because it can be changed into a prime (21211212107) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8156859 + ... + 8159458.

Almost surely, 221211212100 is an apocalyptic number.

21211212100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211212100 is an abundant number, since it is smaller than the sum of its proper divisors (28357761984).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21211212100 is a wasteful number, since it uses less digits than its factorization.

21211212100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16316344 (or 16316337 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21211212100 its reverse (121211212), we get a palindrome (21332423312).

The spelling of 21211212100 in words is "twenty-one billion, two hundred eleven million, two hundred twelve thousand, one hundred".

Divisors: 1 2 4 5 10 13 20 25 26 50 52 65 100 130 260 325 650 1300 16316317 32632634 65265268 81581585 163163170 212112121 326326340 407907925 424224242 815815850 848448484 1060560605 1631631700 2121121210 4242242420 5302803025 10605606050 21211212100