21782329 has 2 divisors, whose sum is σ = 21782330. Its totient is φ = 21782328.

The previous prime is 21782323. The next prime is 21782339. The reversal of 21782329 is 92328712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19053225 + 2729104 = 4365^2 + 1652^2 .

It is a cyclic number.

It is not a de Polignac number, because 21782329 - 2¹⁵ = 21749561 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21782294 and 21782303.

It is not a weakly prime, because it can be changed into another prime (21782323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10891164 + 10891165.

It is an arithmetic number, because the mean of its divisors is an integer number (10891165).

Almost surely, 2^21782329 is an apocalyptic number.

It is an amenable number.

21782329 is a deficient number, since it is larger than the sum of its proper divisors (1).

21782329 is an equidigital number, since it uses as much as digits as its factorization.

21782329 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 34.

The square root of 21782329 is about 4667.1542721449. The cubic root of 21782329 is about 279.2767430862.

The spelling of 21782329 in words is "twenty-one million, seven hundred eighty-two thousand, three hundred twenty-nine".