21024723 has 16 divisors (see below), whose sum is σ = 28528640. Its totient is φ = 13771296.

The previous prime is 21024643. The next prime is 21024743. The reversal of 21024723 is 32742012.

It is not a de Polignac number, because 21024723 - 2⁸ = 21024467 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21024723.

It is not an unprimeable number, because it can be changed into a prime (21024743) 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 15 ways as a sum of consecutive naturals, for example, 52761 + ... + 53157.

It is an arithmetic number, because the mean of its divisors is an integer number (1783040).

Almost surely, 2^21024723 is an apocalyptic number.

21024723 is a deficient number, since it is larger than the sum of its proper divisors (7503917).

21024723 is a wasteful number, since it uses less digits than its factorization.

21024723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 21024723 is about 4585.2724019408. The cubic root of 21024723 is about 276.0006432457. Note that the first 3 decimals are identical.

Adding to 21024723 its reverse (32742012), we get a palindrome (53766735).

The spelling of 21024723 in words is "twenty-one million, twenty-four thousand, seven hundred twenty-three".