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21081630 = 235702721
BaseRepresentation
bin101000001101…
…0111000011110
31110200001120010
41100122320132
520344103010
62031504050
7344122323
oct120327036
943601503
1021081630
1110999a39
127088026
1344a184b
142b2ab4a
151cb6620
hex141ae1e

21081630 has 16 divisors (see below), whose sum is σ = 50595984. Its totient is φ = 5621760.

The previous prime is 21081623. The next prime is 21081631. The reversal of 21081630 is 3618012.

It is a junction number, because it is equal to n+sod(n) for n = 21081597 and 21081606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081631) 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, 351331 + ... + 351390.

It is an arithmetic number, because the mean of its divisors is an integer number (3162249).

Almost surely, 221081630 is an apocalyptic number.

21081630 is an abundant number, since it is smaller than the sum of its proper divisors (29514354).

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

21081630 is a wasteful number, since it uses less digits than its factorization.

21081630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 702731.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21081630 is about 4591.4736196563. The cubic root of 21081630 is about 276.2494331936.

Adding to 21081630 its reverse (3618012), we get a palindrome (24699642).

The spelling of 21081630 in words is "twenty-one million, eighty-one thousand, six hundred thirty".

Divisors: 1 2 3 5 6 10 15 30 702721 1405442 2108163 3513605 4216326 7027210 10540815 21081630