21840829 has 2 divisors, whose sum is σ = 21840830. Its totient is φ = 21840828.

The previous prime is 21840817. The next prime is 21840851. The reversal of 21840829 is 92804812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21483225 + 357604 = 4635^2 + 598^2 .

It is a cyclic number.

It is not a de Polignac number, because 21840829 - 2¹⁷ = 21709757 is a prime.

It is a super-2 number, since 2×21840829² = 954043622814482, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21840794 and 21840803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21840809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10920414 + 10920415.

It is an arithmetic number, because the mean of its divisors is an integer number (10920415).

Almost surely, 2^21840829 is an apocalyptic number.

It is an amenable number.

21840829 is a deficient number, since it is larger than the sum of its proper divisors (1).

21840829 is an equidigital number, since it uses as much as digits as its factorization.

21840829 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 21840829 is about 4673.4172721896. The cubic root of 21840829 is about 279.5265340277.

The spelling of 21840829 in words is "twenty-one million, eight hundred forty thousand, eight hundred twenty-nine".