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20970 = 2325233

20970 has 24 divisors (see below), whose sum is σ = 54756. Its totient is φ = 5568.

The previous prime is 20963. The next prime is 20981. The reversal of 20970 is 7902.

It can be written as a sum of positive squares in 2 ways, for example, as 19881 + 1089 = 141^2 + 33^2 .

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a nialpdrome in base 13 and base 15.

It is an unprimeable number.

20970 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27 + ... + 206.

220970 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20970, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27378).

20970 is an abundant number, since it is smaller than the sum of its proper divisors (33786).

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

20970 is a wasteful number, since it uses less digits than its factorization.

20970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246 (or 243 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 18.

The square root of 20970 is about 144.8102206338. The cubic root of 20970 is about 27.5760977686.

It can be divided in two parts, 20 and 970, that added together give a triangular number (990 = T44).

The spelling of 20970 in words is "twenty thousand, nine hundred seventy".

Divisors: 1 2 3 5 6 9 10 15 18 30 45 90 233 466 699 1165 1398 2097 2330 3495 4194 6990 10485 20970