21308629 has 2 divisors, whose sum is σ = 21308630. Its totient is φ = 21308628.

The previous prime is 21308611. The next prime is 21308653. The reversal of 21308629 is 92680312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21298225 + 10404 = 4615^2 + 102^2 .

It is a cyclic number.

It is not a de Polignac number, because 21308629 - 2¹⁵ = 21275861 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21308629.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21308659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10654314 + 10654315.

It is an arithmetic number, because the mean of its divisors is an integer number (10654315).

Almost surely, 2^21308629 is an apocalyptic number.

It is an amenable number.

21308629 is a deficient number, since it is larger than the sum of its proper divisors (1).

21308629 is an equidigital number, since it uses as much as digits as its factorization.

21308629 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21308629 is about 4616.1270563103. The cubic root of 21308629 is about 277.2374119640.

The spelling of 21308629 in words is "twenty-one million, three hundred eight thousand, six hundred twenty-nine".