21210487 has 2 divisors, whose sum is σ = 21210488. Its totient is φ = 21210486.

The previous prime is 21210463. The next prime is 21210491. The reversal of 21210487 is 78401212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21210487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605243 + 10605244.

It is an arithmetic number, because the mean of its divisors is an integer number (10605244).

Almost surely, 2^21210487 is an apocalyptic number.

21210487 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210487 is an equidigital number, since it uses as much as digits as its factorization.

21210487 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 21210487 is about 4605.4844479164. The cubic root of 21210487 is about 276.8111290521.

Adding to 21210487 its reverse (78401212), we get a palindrome (99611699).

The spelling of 21210487 in words is "twenty-one million, two hundred ten thousand, four hundred eighty-seven".