21050247 has 4 divisors (see below), whose sum is σ = 28067000. Its totient is φ = 14033496.

The previous prime is 21050231. The next prime is 21050251. The reversal of 21050247 is 74205012.

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

It is not a de Polignac number, because 21050247 - 2⁴ = 21050231 is a prime.

It is a super-2 number, since 2×21050247² = 886225797522018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21050287) 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 in 3 ways as a sum of consecutive naturals, for example, 3508372 + ... + 3508377.

It is an arithmetic number, because the mean of its divisors is an integer number (7016750).

Almost surely, 2^21050247 is an apocalyptic number.

21050247 is a deficient number, since it is larger than the sum of its proper divisors (7016753).

21050247 is an equidigital number, since it uses as much as digits as its factorization.

21050247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7016752.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 21050247 is about 4588.0548165862. The cubic root of 21050247 is about 276.1122862800.

Adding to 21050247 its reverse (74205012), we get a palindrome (95255259).

The spelling of 21050247 in words is "twenty-one million, fifty thousand, two hundred forty-seven".