21210587 has 2 divisors, whose sum is σ = 21210588. Its totient is φ = 21210586.

The previous prime is 21210557. The next prime is 21210619. The reversal of 21210587 is 78501212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21210587 - 2¹⁰ = 21209563 is a prime.

It is a Chen prime.

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

It is not a weakly prime, because it can be changed into another prime (21210557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605293 + 10605294.

It is an arithmetic number, because the mean of its divisors is an integer number (10605294).

Almost surely, 2^21210587 is an apocalyptic number.

21210587 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210587 is an equidigital number, since it uses as much as digits as its factorization.

21210587 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 21210587 is about 4605.4953045248. The cubic root of 21210587 is about 276.8115640738.

Adding to 21210587 its reverse (78501212), we get a palindrome (99711799).

The spelling of 21210587 in words is "twenty-one million, two hundred ten thousand, five hundred eighty-seven".