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87721 is a prime number
BaseRepresentation
bin10101011010101001
311110022221
4111122221
510301341
61514041
7513514
oct253251
9143287
1087721
115a9a7
1242921
1330c0a
1423d7b
151aed1
hex156a9

87721 has 2 divisors, whose sum is σ = 87722. Its totient is φ = 87720.

The previous prime is 87719. The next prime is 87739. The reversal of 87721 is 12778.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 68121 + 19600 = 261^2 + 140^2 .

It is a cyclic number.

It is not a de Polignac number, because 87721 - 21 = 87719 is a prime.

Together with 87719, it forms a pair of twin primes.

87721 is a lucky number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43860 + 43861.

It is an arithmetic number, because the mean of its divisors is an integer number (43861).

287721 is an apocalyptic number.

It is an amenable number.

87721 is a deficient number, since it is larger than the sum of its proper divisors (1).

87721 is an equidigital number, since it uses as much as digits as its factorization.

87721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 784, while the sum is 25.

The square root of 87721 is about 296.1773117577. The cubic root of 87721 is about 44.4325451941.

It can be divided in two parts, 877 and 21, that added together give a palindrome (898).

The spelling of 87721 in words is "eighty-seven thousand, seven hundred twenty-one".