21235756 has 12 divisors (see below), whose sum is σ = 37580760. Its totient is φ = 10498400.

The previous prime is 21235741. The next prime is 21235759. The reversal of 21235756 is 65753212.

It is not an unprimeable number, because it can be changed into a prime (21235759) 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 3 ways as a sum of consecutive naturals, for example, 29470 + ... + 30181.

It is an arithmetic number, because the mean of its divisors is an integer number (3131730).

Almost surely, 2^21235756 is an apocalyptic number.

It is an amenable number.

21235756 is a deficient number, since it is larger than the sum of its proper divisors (16345004).

21235756 is a wasteful number, since it uses less digits than its factorization.

21235756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59744 (or 59742 counting only the distinct ones).

The product of its digits is 12600, while the sum is 31.

The square root of 21235756 is about 4608.2269909370. The cubic root of 21235756 is about 276.9210112461.

Adding to 21235756 its reverse (65753212), we get a palindrome (86988968).

The spelling of 21235756 in words is "twenty-one million, two hundred thirty-five thousand, seven hundred fifty-six".