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21530997 = 322392333
BaseRepresentation
bin101001000100…
…0100101110101
31111111212222100
41102020211311
521002442442
62045252313
7351003405
oct122104565
944455870
1021530997
1111176614
127264099
1345cb247
142c06805
151d5484c
hex1488975

21530997 has 6 divisors (see below), whose sum is σ = 31100342. Its totient is φ = 14353992.

The previous prime is 21530989. The next prime is 21531001. The reversal of 21530997 is 79903512.

It can be written as a sum of positive squares in only one way, i.e., 16695396 + 4835601 = 4086^2 + 2199^2 .

It is not a de Polignac number, because 21530997 - 23 = 21530989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1196158 + ... + 1196175.

Almost surely, 221530997 is an apocalyptic number.

It is an amenable number.

21530997 is a deficient number, since it is larger than the sum of its proper divisors (9569345).

21530997 is a wasteful number, since it uses less digits than its factorization.

21530997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2392339 (or 2392336 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 21530997 is about 4640.1505363512. The cubic root of 21530997 is about 278.1984548146.

The spelling of 21530997 in words is "twenty-one million, five hundred thirty thousand, nine hundred ninety-seven".

Divisors: 1 3 9 2392333 7176999 21530997