21580687 has 2 divisors, whose sum is σ = 21580688. Its totient is φ = 21580686.

The previous prime is 21580673. The next prime is 21580697. The reversal of 21580687 is 78608512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21580687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21580697) 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, 10790343 + 10790344.

It is an arithmetic number, because the mean of its divisors is an integer number (10790344).

Almost surely, 2^21580687 is an apocalyptic number.

21580687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21580687 is an equidigital number, since it uses as much as digits as its factorization.

21580687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 21580687 is about 4645.5018028196. The cubic root of 21580687 is about 278.4123024838.

The spelling of 21580687 in words is "twenty-one million, five hundred eighty thousand, six hundred eighty-seven".