21206471 has 16 divisors (see below), whose sum is σ = 25528608. Its totient is φ = 17356800.

The previous prime is 21206443. The next prime is 21206477. The reversal of 21206471 is 17460212.

It is a cyclic number.

It is not a de Polignac number, because 21206471 - 2⁶ = 21206407 is a prime.

It is a super-3 number, since 3×21206471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21206477) 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 15 ways as a sum of consecutive naturals, for example, 4055 + ... + 7671.

It is an arithmetic number, because the mean of its divisors is an integer number (1595538).

Almost surely, 2^21206471 is an apocalyptic number.

21206471 is a deficient number, since it is larger than the sum of its proper divisors (4322137).

21206471 is a wasteful number, since it uses less digits than its factorization.

21206471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3682.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21206471 is about 4605.0484253697. The cubic root of 21206471 is about 276.7936574485.

Adding to 21206471 its reverse (17460212), we get a palindrome (38666683).

The spelling of 21206471 in words is "twenty-one million, two hundred six thousand, four hundred seventy-one".