20721226 has 16 divisors (see below), whose sum is σ = 31651200. Its totient is φ = 10172448.

The previous prime is 20721223. The next prime is 20721263. The reversal of 20721226 is 62212702.

It is a junction number, because it is equal to n+sod(n) for n = 20721197 and 20721206.

It is not an unprimeable number, because it can be changed into a prime (20721223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49245 + ... + 49663.

It is an arithmetic number, because the mean of its divisors is an integer number (1978200).

Almost surely, 2^20721226 is an apocalyptic number.

20721226 is a deficient number, since it is larger than the sum of its proper divisors (10929974).

20721226 is a wasteful number, since it uses less digits than its factorization.

20721226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 813.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 20721226 is about 4552.0573370730. The cubic root of 20721226 is about 274.6661557656. Note that the first 3 decimals are identical.

Adding to 20721226 its reverse (62212702), we get a palindrome (82933928).

The spelling of 20721226 in words is "twenty million, seven hundred twenty-one thousand, two hundred twenty-six".