21032747 has 4 divisors (see below), whose sum is σ = 21269160. Its totient is φ = 20796336.

The previous prime is 21032731. The next prime is 21032773. The reversal of 21032747 is 74723012.

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 21032747 - 2⁴ = 21032731 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21032777) 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, 118073 + ... + 118250.

It is an arithmetic number, because the mean of its divisors is an integer number (5317290).

Almost surely, 2^21032747 is an apocalyptic number.

21032747 is a deficient number, since it is larger than the sum of its proper divisors (236413).

21032747 is an equidigital number, since it uses as much as digits as its factorization.

21032747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236412.

The product of its (nonzero) digits is 2352, while the sum is 26.

The square root of 21032747 is about 4586.1472937532. The cubic root of 21032747 is about 276.0357502875.

Adding to 21032747 its reverse (74723012), we get a palindrome (95755759).

The spelling of 21032747 in words is "twenty-one million, thirty-two thousand, seven hundred forty-seven".