21124247 has 8 divisors (see below), whose sum is σ = 21544320. Its totient is φ = 20708280.

The previous prime is 21124199. The next prime is 21124253. The reversal of 21124247 is 74242112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21124247 - 2¹⁶ = 21058711 is a prime.

It is a super-2 number, since 2×21124247² = 892467622634018, 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 (21124277) 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 7 ways as a sum of consecutive naturals, for example, 10622 + ... + 12452.

It is an arithmetic number, because the mean of its divisors is an integer number (2693040).

Almost surely, 2^21124247 is an apocalyptic number.

21124247 is a deficient number, since it is larger than the sum of its proper divisors (420073).

21124247 is a wasteful number, since it uses less digits than its factorization.

21124247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2053.

The product of its digits is 896, while the sum is 23.

The square root of 21124247 is about 4596.1121613816. The cubic root of 21124247 is about 276.4354560947.

Adding to 21124247 its reverse (74242112), we get a palindrome (95366359).

The spelling of 21124247 in words is "twenty-one million, one hundred twenty-four thousand, two hundred forty-seven".