21682613 has 2 divisors, whose sum is σ = 21682614. Its totient is φ = 21682612.

The previous prime is 21682589. The next prime is 21682627. The reversal of 21682613 is 31628612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15816529 + 5866084 = 3977^2 + 2422^2 .

It is a cyclic number.

It is not a de Polignac number, because 21682613 - 2⁸ = 21682357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21682643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10841306 + 10841307.

It is an arithmetic number, because the mean of its divisors is an integer number (10841307).

Almost surely, 2^21682613 is an apocalyptic number.

It is an amenable number.

21682613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21682613 is an equidigital number, since it uses as much as digits as its factorization.

21682613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 29.

The square root of 21682613 is about 4656.4592771762. The cubic root of 21682613 is about 278.8499297853.

The spelling of 21682613 in words is "twenty-one million, six hundred eighty-two thousand, six hundred thirteen".