21187059 has 4 divisors (see below), whose sum is σ = 28249416. Its totient is φ = 14124704.

The previous prime is 21187027. The next prime is 21187063. The reversal of 21187059 is 95078112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21187059 - 2⁵ = 21187027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21187079) 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 in 3 ways as a sum of consecutive naturals, for example, 3531174 + ... + 3531179.

It is an arithmetic number, because the mean of its divisors is an integer number (7062354).

Almost surely, 2^21187059 is an apocalyptic number.

21187059 is a deficient number, since it is larger than the sum of its proper divisors (7062357).

21187059 is an equidigital number, since it uses as much as digits as its factorization.

21187059 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7062356.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 21187059 is about 4602.9402559668. The cubic root of 21187059 is about 276.7091744496.

The spelling of 21187059 in words is "twenty-one million, one hundred eighty-seven thousand, fifty-nine".