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21313531 is a prime number
BaseRepresentation
bin101000101001…
…1011111111011
31111002211200001
41101103133323
520424013111
62040453431
7346106401
oct121233773
944084601
1021313531
1111038198
12717a277
134553275
142b8b471
151d101c1
hex14537fb

21313531 has 2 divisors, whose sum is σ = 21313532. Its totient is φ = 21313530.

The previous prime is 21313493. The next prime is 21313541. The reversal of 21313531 is 13531312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-21313531 is a prime.

It is a super-2 number, since 2×213135312 = 908533207375922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21313499 and 21313508.

It is not a weakly prime, because it can be changed into another prime (21313541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656765 + 10656766.

It is an arithmetic number, because the mean of its divisors is an integer number (10656766).

Almost surely, 221313531 is an apocalyptic number.

21313531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21313531 is an equidigital number, since it uses as much as digits as its factorization.

21313531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 270, while the sum is 19.

The square root of 21313531 is about 4616.6579903649. The cubic root of 21313531 is about 277.2586696056.

Adding to 21313531 its reverse (13531312), we get a palindrome (34844843).

The spelling of 21313531 in words is "twenty-one million, three hundred thirteen thousand, five hundred thirty-one".