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87139881 = 347314737
BaseRepresentation
bin1010011000110…
…10011000101001
320001222011110000
411030122120221
5134301434011
612351413213
72105451063
oct514323051
9201864400
1087139881
1145208534
1225224209
131509017a
14b804733
1579b4356
hex531a629

87139881 has 20 divisors (see below), whose sum is σ = 131964052. Its totient is φ = 57293568.

The previous prime is 87139879. The next prime is 87139919. The reversal of 87139881 is 18893178.

It can be written as a sum of positive squares in 2 ways, for example, as 62726400 + 24413481 = 7920^2 + 4941^2 .

It is not a de Polignac number, because 87139881 - 21 = 87139879 is a prime.

It is a super-2 number, since 2×871398812 = 15186717721388322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87139831) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1456 + ... + 13281.

Almost surely, 287139881 is an apocalyptic number.

87139881 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

87139881 is a deficient number, since it is larger than the sum of its proper divisors (44824171).

87139881 is a wasteful number, since it uses less digits than its factorization.

87139881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14822 (or 14813 counting only the distinct ones).

The product of its digits is 96768, while the sum is 45.

The square root of 87139881 is about 9334.8744501466. The cubic root of 87139881 is about 443.3421136947.

The spelling of 87139881 in words is "eighty-seven million, one hundred thirty-nine thousand, eight hundred eighty-one".

Divisors: 1 3 9 27 73 81 219 657 1971 5913 14737 44211 132633 397899 1075801 1193697 3227403 9682209 29046627 87139881