21587893 has 2 divisors, whose sum is σ = 21587894. Its totient is φ = 21587892.

The previous prime is 21587887. The next prime is 21587921. The reversal of 21587893 is 39878512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11303044 + 10284849 = 3362^2 + 3207^2 .

It is a cyclic number.

It is not a de Polignac number, because 21587893 - 2⁹ = 21587381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21581893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10793946 + 10793947.

It is an arithmetic number, because the mean of its divisors is an integer number (10793947).

Almost surely, 2^21587893 is an apocalyptic number.

It is an amenable number.

21587893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21587893 is an equidigital number, since it uses as much as digits as its factorization.

21587893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 43.

The square root of 21587893 is about 4646.2773270652. The cubic root of 21587893 is about 278.4432872217.

The spelling of 21587893 in words is "twenty-one million, five hundred eighty-seven thousand, eight hundred ninety-three".