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31220 = 2257223
BaseRepresentation
bin111100111110100
31120211022
413213310
51444340
6400312
7160010
oct74764
946738
1031220
1121502
1216098
1311297
14b540
1593b5
hex79f4

31220 has 24 divisors (see below), whose sum is σ = 75264. Its totient is φ = 10656.

The previous prime is 31219. The next prime is 31223. The reversal of 31220 is 2213.

31220 = T99 + T100 + ... + T104.

It is a nialpdrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 31198 and 31207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29 + ... + 251.

It is an arithmetic number, because the mean of its divisors is an integer number (3136).

231220 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37632).

31220 is an abundant number, since it is smaller than the sum of its proper divisors (44044).

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

31220 is a wasteful number, since it uses less digits than its factorization.

31220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239 (or 237 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 8.

The square root of 31220 is about 176.6918221084. The cubic root of 31220 is about 31.4879436519.

Adding to 31220 its reverse (2213), we get a palindrome (33433).

The spelling of 31220 in words is "thirty-one thousand, two hundred twenty".

Divisors: 1 2 4 5 7 10 14 20 28 35 70 140 223 446 892 1115 1561 2230 3122 4460 6244 7805 15610 31220