21506341 has 2 divisors, whose sum is σ = 21506342. Its totient is φ = 21506340.

The previous prime is 21506339. The next prime is 21506369. The reversal of 21506341 is 14360512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15484225 + 6022116 = 3935^2 + 2454^2 .

It is a cyclic number.

It is not a de Polignac number, because 21506341 - 2¹ = 21506339 is a prime.

Together with 21506339, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21506041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753170 + 10753171.

It is an arithmetic number, because the mean of its divisors is an integer number (10753171).

Almost surely, 2^21506341 is an apocalyptic number.

It is an amenable number.

21506341 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506341 is an equidigital number, since it uses as much as digits as its factorization.

21506341 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21506341 is about 4637.4929649542. The cubic root of 21506341 is about 278.0922222198.

Adding to 21506341 its reverse (14360512), we get a palindrome (35866853).

The spelling of 21506341 in words is "twenty-one million, five hundred six thousand, three hundred forty-one".