21315583 has 2 divisors, whose sum is σ = 21315584. Its totient is φ = 21315582.

The previous prime is 21315571. The next prime is 21315599. The reversal of 21315583 is 38551312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21315583 - 2¹⁷ = 21184511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21315563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10657791 + 10657792.

It is an arithmetic number, because the mean of its divisors is an integer number (10657792).

Almost surely, 2^21315583 is an apocalyptic number.

21315583 is a deficient number, since it is larger than the sum of its proper divisors (1).

21315583 is an equidigital number, since it uses as much as digits as its factorization.

21315583 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3600, while the sum is 28.

The square root of 21315583 is about 4616.8802237008. The cubic root of 21315583 is about 277.2675671855.

Adding to 21315583 its reverse (38551312), we get a palindrome (59866895).

The spelling of 21315583 in words is "twenty-one million, three hundred fifteen thousand, five hundred eighty-three".