654440021 has 2 divisors, whose sum is σ = 654440022. Its totient is φ = 654440020.

The previous prime is 654440011. The next prime is 654440027. The reversal of 654440021 is 120044456.

654440021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 357739396 + 296700625 = 18914^2 + 17225^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-654440021 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (654440027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 327220010 + 327220011.

It is an arithmetic number, because the mean of its divisors is an integer number (327220011).

Almost surely, 2^654440021 is an apocalyptic number.

It is an amenable number.

654440021 is a deficient number, since it is larger than the sum of its proper divisors (1).

654440021 is an equidigital number, since it uses as much as digits as its factorization.

654440021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3840, while the sum is 26.

The square root of 654440021 is about 25582.0253498428. The cubic root of 654440021 is about 868.2070004901.

Adding to 654440021 its reverse (120044456), we get a palindrome (774484477).

The spelling of 654440021 in words is "six hundred fifty-four million, four hundred forty thousand, twenty-one".