21006753 has 16 divisors (see below), whose sum is σ = 28664832. Its totient is φ = 13680000.

The previous prime is 21006743. The next prime is 21006779. The reversal of 21006753 is 35760012.

It is not a de Polignac number, because 21006753 - 2⁴ = 21006737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21006703) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34653 + ... + 35253.

It is an arithmetic number, because the mean of its divisors is an integer number (1791552).

Almost surely, 2^21006753 is an apocalyptic number.

It is an amenable number.

21006753 is a deficient number, since it is larger than the sum of its proper divisors (7658079).

21006753 is a wasteful number, since it uses less digits than its factorization.

21006753 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 856.

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 21006753 is about 4583.3124484373. The cubic root of 21006753 is about 275.9219875084.

Adding to 21006753 its reverse (35760012), we get a palindrome (56766765).

The spelling of 21006753 in words is "twenty-one million, six thousand, seven hundred fifty-three".