21420233 has 2 divisors, whose sum is σ = 21420234. Its totient is φ = 21420232.

The previous prime is 21420227. The next prime is 21420251. The reversal of 21420233 is 33202412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21418384 + 1849 = 4628^2 + 43^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420233 - 2⁶ = 21420169 is a prime.

It is not a weakly prime, because it can be changed into another prime (21420263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710116 + 10710117.

It is an arithmetic number, because the mean of its divisors is an integer number (10710117).

Almost surely, 2^21420233 is an apocalyptic number.

It is an amenable number.

21420233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420233 is an equidigital number, since it uses as much as digits as its factorization.

21420233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21420233 is about 4628.1997580053. The cubic root of 21420233 is about 277.7205799683.

Adding to 21420233 its reverse (33202412), we get a palindrome (54622645).

The spelling of 21420233 in words is "twenty-one million, four hundred twenty thousand, two hundred thirty-three".