21440687 has 2 divisors, whose sum is σ = 21440688. Its totient is φ = 21440686.

The previous prime is 21440681. The next prime is 21440693. The reversal of 21440687 is 78604412.

It is a balanced prime because it is at equal distance from previous prime (21440681) and next prime (21440693).

It is a cyclic number.

It is not a de Polignac number, because 21440687 - 2⁸ = 21440431 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21440681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720343 + 10720344.

It is an arithmetic number, because the mean of its divisors is an integer number (10720344).

Almost surely, 2^21440687 is an apocalyptic number.

21440687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440687 is an equidigital number, since it uses as much as digits as its factorization.

21440687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 21440687 is about 4630.4089452229. The cubic root of 21440687 is about 277.8089495270.

The spelling of 21440687 in words is "twenty-one million, four hundred forty thousand, six hundred eighty-seven".