20721230 has 8 divisors (see below), whose sum is σ = 37298232. Its totient is φ = 8288488.

The previous prime is 20721223. The next prime is 20721263. The reversal of 20721230 is 3212702.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20721199 and 20721208.

It is a congruent number.

It is an unprimeable number.

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, 1036052 + ... + 1036071.

It is an arithmetic number, because the mean of its divisors is an integer number (4662279).

Almost surely, 2^20721230 is an apocalyptic number.

20721230 is a deficient number, since it is larger than the sum of its proper divisors (16577002).

20721230 is a wasteful number, since it uses less digits than its factorization.

20721230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2072130.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 20721230 is about 4552.0577764347. The cubic root of 20721230 is about 274.6661734394. Note that the first 3 decimals are identical.

Adding to 20721230 its reverse (3212702), we get a palindrome (23933932).

The spelling of 20721230 in words is "twenty million, seven hundred twenty-one thousand, two hundred thirty".