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BaseRepresentation
bin10101011110110110
311110200220
4111132312
510303430
61515210
7514350
oct253666
9143626
1087990
1160121
1242b06
1331086
14240d0
151b110
hex157b6

87990 has 32 divisors (see below), whose sum is σ = 241920. Its totient is φ = 20064.

The previous prime is 87977. The next prime is 87991. The reversal of 87990 is 9978.

It can be divided in two parts, 879 and 90, that added together give a palindrome (969).

87990 is a nontrivial binomial coefficient, being equal to C(420, 2).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87991) by changing a digit.

87990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 15 ways as a sum of consecutive naturals, for example, 1 + ... + 419.

It is an arithmetic number, because the mean of its divisors is an integer number (7560).

287990 is an apocalyptic number.

87990 is the 419-th triangular number and also the 210-th hexagonal number.

It is a practical number, because each smaller number is the sum of distinct divisors of 87990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120960).

87990 is an abundant number, since it is smaller than the sum of its proper divisors (153930).

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

87990 is a wasteful number, since it uses less digits than its factorization.

87990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 436.

The product of its (nonzero) digits is 4536, while the sum is 33.

The square root of 87990 is about 296.6310840084. The cubic root of 87990 is about 44.4779169142.

The spelling of 87990 in words is "eighty-seven thousand, nine hundred ninety".