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21121999 is a prime number
BaseRepresentation
bin101000010010…
…0101111001111
31110202002221021
41100210233033
520401400444
62032415011
7344351113
oct120445717
943662837
1021121999
1110a172a8
1270a7467
1344b7032
142b3b743
151cc3584
hex1424bcf

21121999 has 2 divisors, whose sum is σ = 21122000. Its totient is φ = 21121998.

The previous prime is 21121979. The next prime is 21122009. The reversal of 21121999 is 99912112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21121999 - 25 = 21121967 is a prime.

It is a super-2 number, since 2×211219992 = 892277683512002, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21121909) 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 as a sum of consecutive naturals, namely, 10560999 + 10561000.

It is an arithmetic number, because the mean of its divisors is an integer number (10561000).

Almost surely, 221121999 is an apocalyptic number.

21121999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121999 is an equidigital number, since it uses as much as digits as its factorization.

21121999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2916, while the sum is 34.

The square root of 21121999 is about 4595.8676003558. The cubic root of 21121999 is about 276.4256498445.

The spelling of 21121999 in words is "twenty-one million, one hundred twenty-one thousand, nine hundred ninety-nine".