21344987 has 2 divisors, whose sum is σ = 21344988. Its totient is φ = 21344986.

The previous prime is 21344951. The next prime is 21345001. The reversal of 21344987 is 78944312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21344987 - 2¹⁴ = 21328603 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21344987.

It is not a weakly prime, because it can be changed into another prime (21334987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672493 + 10672494.

It is an arithmetic number, because the mean of its divisors is an integer number (10672494).

Almost surely, 2^21344987 is an apocalyptic number.

21344987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21344987 is an equidigital number, since it uses as much as digits as its factorization.

21344987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 38.

The square root of 21344987 is about 4620.0635277018. The cubic root of 21344987 is about 277.3950018047.

The spelling of 21344987 in words is "twenty-one million, three hundred forty-four thousand, nine hundred eighty-seven".