21782869 has 2 divisors, whose sum is σ = 21782870. Its totient is φ = 21782868.

The previous prime is 21782861. The next prime is 21782903. The reversal of 21782869 is 96828712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15507844 + 6275025 = 3938^2 + 2505^2 .

It is a cyclic number.

It is not a de Polignac number, because 21782869 - 2³ = 21782861 is a prime.

It is a super-2 number, since 2×21782869² = 948986763742322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21782861) 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, 10891434 + 10891435.

It is an arithmetic number, because the mean of its divisors is an integer number (10891435).

Almost surely, 2^21782869 is an apocalyptic number.

It is an amenable number.

21782869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21782869 is an equidigital number, since it uses as much as digits as its factorization.

21782869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96768, while the sum is 43.

The square root of 21782869 is about 4667.2121228845. The cubic root of 21782869 is about 279.2790508926.

It can be divided in two parts, 2 and 1782869, that added together give a palindrome (1782871).

The spelling of 21782869 in words is "twenty-one million, seven hundred eighty-two thousand, eight hundred sixty-nine".