20226721 has 2 divisors, whose sum is σ = 20226722. Its totient is φ = 20226720.

The previous prime is 20226707. The next prime is 20226737. The reversal of 20226721 is 12762202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11316496 + 8910225 = 3364^2 + 2985^2 .

It is a cyclic number.

It is not a de Polignac number, because 20226721 - 2¹³ = 20218529 is a prime.

It is equal to p_1284070 and since 20226721 and 1284070 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 20226692 and 20226701.

It is not a weakly prime, because it can be changed into another prime (20226751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10113360 + 10113361.

It is an arithmetic number, because the mean of its divisors is an integer number (10113361).

Almost surely, 2^20226721 is an apocalyptic number.

It is an amenable number.

20226721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20226721 is an equidigital number, since it uses as much as digits as its factorization.

20226721 is an evil number, because the sum of its binary digits is even.

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

The square root of 20226721 is about 4497.4127006536. The cubic root of 20226721 is about 272.4636025791.

Adding to 20226721 its reverse (12762202), we get a palindrome (32988923).

The spelling of 20226721 in words is "twenty million, two hundred twenty-six thousand, seven hundred twenty-one".