21316 has 9 divisors (see below), whose sum is σ = 37821. Its totient is φ = 10512.

The previous prime is 21313. The next prime is 21317. The reversal of 21316 is 61312.

21316 = T_{145} + T_{146}.

The square root of 21316 is 146.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 12100 + 9216 = 110^2 + 96^2 .

It is a Duffinian number.

It is a junction number, because it is equal to *n*+sod(*n*) for *n* = 21296 and 21305.

It is not an unprimeable number, because it can be changed into a prime (21313) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 256 + ... + 328.

2^{21316} is an apocalyptic number.

21316 is the 146-th square number.

It is an amenable number.

21316 is a deficient number, since it is larger than the sum of its proper divisors (16505).

21316 is an equidigital number, since it uses as much as digits as its factorization.

21316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150 (or 75 counting only the distinct ones).

The product of its digits is 36, while the sum is 13.

The cubic root of 21316 is about 27.7269375250.

Multiplying 21316 by its product of digits (36), we get a square (767376 = 876^{2}).

Adding to 21316 its reverse (61312), we get a palindrome (82628).

The spelling of 21316 in words is "twenty-one thousand, three hundred sixteen".

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