21638069 has 2 divisors, whose sum is σ = 21638070. Its totient is φ = 21638068.

The previous prime is 21638063. The next prime is 21638117. The reversal of 21638069 is 96083612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13965169 + 7672900 = 3737^2 + 2770^2 .

It is a cyclic number.

It is not a de Polignac number, because 21638069 - 2¹² = 21633973 is a prime.

It is a super-2 number, since 2×21638069² = 936412060097522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21638063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10819034 + 10819035.

It is an arithmetic number, because the mean of its divisors is an integer number (10819035).

Almost surely, 2^21638069 is an apocalyptic number.

It is an amenable number.

21638069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21638069 is an equidigital number, since it uses as much as digits as its factorization.

21638069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21638069 is about 4651.6737847790. The cubic root of 21638069 is about 278.6588457000.

The spelling of 21638069 in words is "twenty-one million, six hundred thirty-eight thousand, sixty-nine".