21806469 has 8 divisors (see below), whose sum is σ = 32305920. Its totient is φ = 14537628.

The previous prime is 21806467. The next prime is 21806483. The reversal of 21806469 is 96460812.

21806469 is a `hidden beast` number, since 2 + 1 + 8 + 0 + 646 + 9 = 666.

It is not a de Polignac number, because 21806469 - 2¹ = 21806467 is a prime.

It is a super-2 number, since 2×21806469² = 951044180495922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21806467) 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 in 7 ways as a sum of consecutive naturals, for example, 403797 + ... + 403850.

It is an arithmetic number, because the mean of its divisors is an integer number (4038240).

Almost surely, 2^21806469 is an apocalyptic number.

It is an amenable number.

21806469 is a deficient number, since it is larger than the sum of its proper divisors (10499451).

21806469 is an equidigital number, since it uses as much as digits as its factorization.

21806469 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 807656 (or 807650 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 21806469 is about 4669.7397143738. The cubic root of 21806469 is about 279.3798733441.

It can be divided in two parts, 2180 and 6469, that added together give a square (8649 = 93²).

The spelling of 21806469 in words is "twenty-one million, eight hundred six thousand, four hundred sixty-nine".