21738811 has 2 divisors, whose sum is σ = 21738812. Its totient is φ = 21738810.

The previous prime is 21738809. The next prime is 21738817. The reversal of 21738811 is 11883712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21738811 - 2¹ = 21738809 is a prime.

Together with 21738809, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21738817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10869405 + 10869406.

It is an arithmetic number, because the mean of its divisors is an integer number (10869406).

Almost surely, 2^21738811 is an apocalyptic number.

21738811 is a deficient number, since it is larger than the sum of its proper divisors (1).

21738811 is an equidigital number, since it uses as much as digits as its factorization.

21738811 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2688, while the sum is 31.

The square root of 21738811 is about 4662.4897855116. The cubic root of 21738811 is about 279.0906340005.

The spelling of 21738811 in words is "twenty-one million, seven hundred thirty-eight thousand, eight hundred eleven".