21235747 has 12 divisors (see below), whose sum is σ = 23303280. Its totient is φ = 19236960.

The previous prime is 21235741. The next prime is 21235759. The reversal of 21235747 is 74753212.

It is not a de Polignac number, because 21235747 - 2¹⁹ = 20711459 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21235741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 48154 + ... + 48592.

It is an arithmetic number, because the mean of its divisors is an integer number (1941940).

Almost surely, 2^21235747 is an apocalyptic number.

21235747 is a deficient number, since it is larger than the sum of its proper divisors (2067533).

21235747 is an equidigital number, since it uses as much as digits as its factorization.

21235747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 574 (or 513 counting only the distinct ones).

The product of its digits is 11760, while the sum is 31.

The square root of 21235747 is about 4608.2260144225. The cubic root of 21235747 is about 276.9209721251.

Adding to 21235747 its reverse (74753212), we get a palindrome (95988959).

The spelling of 21235747 in words is "twenty-one million, two hundred thirty-five thousand, seven hundred forty-seven".