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21100001 = 131623077
BaseRepresentation
bin101000001111…
…1010111100001
31110200222202112
41100133113201
520400200001
62032125105
7344230016
oct120372741
943628675
1021100001
1110a0181a
127096795
1344aa010
142b3370d
151cbbcbb
hex141f5e1

21100001 has 4 divisors (see below), whose sum is σ = 22723092. Its totient is φ = 19476912.

The previous prime is 21099977. The next prime is 21100003. The reversal of 21100001 is 10000112.

Adding to 21100001 its reverse (10000112), we get a palindrome (31100113).

Multipling 21100001 by its reverse (10000112), we get a palindrome (211002373200112).

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 14592400 + 6507601 = 3820^2 + 2551^2 .

It is a de Polignac number, because none of the positive numbers 2k-21100001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21100003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 811526 + ... + 811551.

It is an arithmetic number, because the mean of its divisors is an integer number (5680773).

Almost surely, 221100001 is an apocalyptic number.

It is an amenable number.

21100001 is a deficient number, since it is larger than the sum of its proper divisors (1623091).

21100001 is a wasteful number, since it uses less digits than its factorization.

21100001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1623090.

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 21100001 is about 4593.4737399924. The cubic root of 21100001 is about 276.3296531909.

The spelling of 21100001 in words is "twenty-one million, one hundred thousand, one".

Divisors: 1 13 1623077 21100001