21560387 has 2 divisors, whose sum is σ = 21560388. Its totient is φ = 21560386.

The previous prime is 21560377. The next prime is 21560401. The reversal of 21560387 is 78306512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21560387 - 2⁶ = 21560323 is a prime.

It is not a weakly prime, because it can be changed into another prime (21560317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10780193 + 10780194.

It is an arithmetic number, because the mean of its divisors is an integer number (10780194).

Almost surely, 2^21560387 is an apocalyptic number.

21560387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21560387 is an equidigital number, since it uses as much as digits as its factorization.

21560387 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21560387 is about 4643.3163794857. The cubic root of 21560387 is about 278.3249783748.

Adding to 21560387 its reverse (78306512), we get a palindrome (99866899).

The spelling of 21560387 in words is "twenty-one million, five hundred sixty thousand, three hundred eighty-seven".