21170587 has 2 divisors, whose sum is σ = 21170588. Its totient is φ = 21170586.

The previous prime is 21170581. The next prime is 21170629. The reversal of 21170587 is 78507112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21170587 - 2¹⁵ = 21137819 is a prime.

It is not a weakly prime, because it can be changed into another prime (21170581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585293 + 10585294.

It is an arithmetic number, because the mean of its divisors is an integer number (10585294).

Almost surely, 2^21170587 is an apocalyptic number.

21170587 is a deficient number, since it is larger than the sum of its proper divisors (1).

21170587 is an equidigital number, since it uses as much as digits as its factorization.

21170587 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 21170587 is about 4601.1506169653. The cubic root of 21170587 is about 276.6374461486.

Adding to 21170587 its reverse (78507112), we get a palindrome (99677699).

The spelling of 21170587 in words is "twenty-one million, one hundred seventy thousand, five hundred eighty-seven".