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21438891 = 33794033
BaseRepresentation
bin101000111001…
…0000110101011
31111100012122000
41101302012223
520442021031
62043302043
7350141025
oct121620653
944305560
1021438891
11111133a1
12721a923
134598346
142bc1015
151d373e6
hex14721ab

21438891 has 8 divisors (see below), whose sum is σ = 31761360. Its totient is φ = 14292576.

The previous prime is 21438881. The next prime is 21438913. The reversal of 21438891 is 19883412.

It is not a de Polignac number, because 21438891 - 26 = 21438827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21438881) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 396990 + ... + 397043.

It is an arithmetic number, because the mean of its divisors is an integer number (3970170).

Almost surely, 221438891 is an apocalyptic number.

21438891 is a deficient number, since it is larger than the sum of its proper divisors (10322469).

21438891 is an equidigital number, since it uses as much as digits as its factorization.

21438891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 794042 (or 794036 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 21438891 is about 4630.2150058070. The cubic root of 21438891 is about 277.8011923315.

It can be divided in two parts, 2 and 1438891, that multiplied together give a palindrome (2877782).

The spelling of 21438891 in words is "twenty-one million, four hundred thirty-eight thousand, eight hundred ninety-one".

Divisors: 1 3 9 27 794033 2382099 7146297 21438891