21586393 has 2 divisors, whose sum is σ = 21586394. Its totient is φ = 21586392.

The previous prime is 21586381. The next prime is 21586399. The reversal of 21586393 is 39368512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11269449 + 10316944 = 3357^2 + 3212^2 .

It is a cyclic number.

It is not a de Polignac number, because 21586393 - 2¹⁷ = 21455321 is a prime.

It is not a weakly prime, because it can be changed into another prime (21586399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10793196 + 10793197.

It is an arithmetic number, because the mean of its divisors is an integer number (10793197).

Almost surely, 2^21586393 is an apocalyptic number.

It is an amenable number.

21586393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21586393 is an equidigital number, since it uses as much as digits as its factorization.

21586393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 37.

The square root of 21586393 is about 4646.1159047101. The cubic root of 21586393 is about 278.4368380111.

The spelling of 21586393 in words is "twenty-one million, five hundred eighty-six thousand, three hundred ninety-three".