21585673 has 2 divisors, whose sum is σ = 21585674. Its totient is φ = 21585672.

The previous prime is 21585671. The next prime is 21585677. The reversal of 21585673 is 37658512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21557449 + 28224 = 4643^2 + 168^2 .

It is a cyclic number.

It is not a de Polignac number, because 21585673 - 2¹ = 21585671 is a prime.

Together with 21585671, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21585671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10792836 + 10792837.

It is an arithmetic number, because the mean of its divisors is an integer number (10792837).

Almost surely, 2^21585673 is an apocalyptic number.

It is an amenable number.

21585673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21585673 is an equidigital number, since it uses as much as digits as its factorization.

21585673 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50400, while the sum is 37.

The square root of 21585673 is about 4646.0384199875. The cubic root of 21585673 is about 278.4337422839.

The spelling of 21585673 in words is "twenty-one million, five hundred eighty-five thousand, six hundred seventy-three".