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81390033 = 32175310037
BaseRepresentation
bin1001101100111…
…10100111010001
312200011001010200
410312132213101
5131313440113
612024245413
72005542504
oct466364721
9180131120
1081390033
1141a4059a
1223310869
1313b28caa
14ab4913b
15722a873
hex4d9e9d1

81390033 has 24 divisors (see below), whose sum is σ = 126840168. Its totient is φ = 50099712.

The previous prime is 81390019. The next prime is 81390061. The reversal of 81390033 is 33009318.

It can be written as a sum of positive squares in 4 ways, for example, as 23736384 + 57653649 = 4872^2 + 7593^2 .

It is not a de Polignac number, because 81390033 - 213 = 81381841 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81389979 and 81390006.

It is not an unprimeable number, because it can be changed into a prime (81390073) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3091 + ... + 13127.

It is an arithmetic number, because the mean of its divisors is an integer number (5285007).

Almost surely, 281390033 is an apocalyptic number.

It is an amenable number.

81390033 is a deficient number, since it is larger than the sum of its proper divisors (45450135).

81390033 is a wasteful number, since it uses less digits than its factorization.

81390033 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10113 (or 10110 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

The square root of 81390033 is about 9021.6424779527. The cubic root of 81390033 is about 433.3682345985.

It can be divided in two parts, 8 and 1390033, that added together give a square (1390041 = 11792).

The spelling of 81390033 in words is "eighty-one million, three hundred ninety thousand, thirty-three".

Divisors: 1 3 9 17 51 53 153 159 477 901 2703 8109 10037 30111 90333 170629 511887 531961 1535661 1595883 4787649 9043337 27130011 81390033