21474581 has 2 divisors, whose sum is σ = 21474582. Its totient is φ = 21474580.

The previous prime is 21474559. The next prime is 21474619. The reversal of 21474581 is 18547412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21473956 + 625 = 4634^2 + 25^2 .

It is a cyclic number.

It is not a de Polignac number, because 21474581 - 2⁶ = 21474517 is a prime.

It is a super-2 number, since 2×21474581² = 922315258251122, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21474511) 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 as a sum of consecutive naturals, namely, 10737290 + 10737291.

It is an arithmetic number, because the mean of its divisors is an integer number (10737291).

Almost surely, 2^21474581 is an apocalyptic number.

It is an amenable number.

21474581 is a deficient number, since it is larger than the sum of its proper divisors (1).

21474581 is an equidigital number, since it uses as much as digits as its factorization.

21474581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8960, while the sum is 32.

The square root of 21474581 is about 4634.0674358494. The cubic root of 21474581 is about 277.9552616791.

The spelling of 21474581 in words is "twenty-one million, four hundred seventy-four thousand, five hundred eighty-one".