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21868749 = 3272172917
BaseRepresentation
bin101001101101…
…1000011001101
31112011001021200
41103123003031
521044244444
62100420113
7353611200
oct123330315
945131250
1021868749
1111387351
1273a7639
1346b8bb6
142c93937
151dbe969
hex14db0cd

21868749 has 36 divisors (see below), whose sum is σ = 38920284. Its totient is φ = 11757312.

The previous prime is 21868723. The next prime is 21868751. The reversal of 21868749 is 94786812.

It can be written as a sum of positive squares in 2 ways, for example, as 20385225 + 1483524 = 4515^2 + 1218^2 .

It is not a de Polignac number, because 21868749 - 28 = 21868493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21868709) 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 35 ways as a sum of consecutive naturals, for example, 6039 + ... + 8955.

It is an arithmetic number, because the mean of its divisors is an integer number (1081119).

Almost surely, 221868749 is an apocalyptic number.

It is an amenable number.

21868749 is a deficient number, since it is larger than the sum of its proper divisors (17051535).

21868749 is a wasteful number, since it uses less digits than its factorization.

21868749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2954 (or 2944 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21868749 is about 4676.4034257108. The cubic root of 21868749 is about 279.6455932698.

The spelling of 21868749 in words is "twenty-one million, eight hundred sixty-eight thousand, seven hundred forty-nine".

Divisors: 1 3 7 9 17 21 49 51 63 119 147 153 357 441 833 1071 2499 2917 7497 8751 20419 26253 49589 61257 142933 148767 183771 347123 428799 446301 1041369 1286397 2429861 3124107 7289583 21868749