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21402 = 2322941
BaseRepresentation
bin101001110011010
31002100200
411032122
51141102
6243030
7116253
oct51632
932320
1021402
1115097
1210476
139984
147b2a
15651c
hex539a

21402 has 24 divisors (see below), whose sum is σ = 49140. Its totient is φ = 6720.

The previous prime is 21401. The next prime is 21407. The reversal of 21402 is 20412.

21402 = T23 + T24 + ... + T51.

It can be written as a sum of positive squares in 2 ways, for example, as 19881 + 1521 = 141^2 + 39^2 .

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a nialpdrome in base 13.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21402.

It is not an unprimeable number, because it can be changed into a prime (21401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 502 + ... + 542.

221402 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21402, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24570).

21402 is an abundant number, since it is smaller than the sum of its proper divisors (27738).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21402 is a wasteful number, since it uses less digits than its factorization.

21402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78 (or 75 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 21402 is about 146.2942240828. The cubic root of 21402 is about 27.7641758592.

Adding to 21402 its reverse (20412), we get a palindrome (41814).

Subtracting from 21402 its reverse (20412), we obtain a triangular number (990 = T44).

The spelling of 21402 in words is "twenty-one thousand, four hundred two", and thus it is an iban number.

Divisors: 1 2 3 6 9 18 29 41 58 82 87 123 174 246 261 369 522 738 1189 2378 3567 7134 10701 21402