404120021 has 2 divisors, whose sum is σ = 404120022. Its totient is φ = 404120020.

The previous prime is 404119981. The next prime is 404120023. The reversal of 404120021 is 120021404.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 265233796 + 138886225 = 16286^2 + 11785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-404120021 is a prime.

Together with 404120023, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 404119978 and 404120005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (404120023) by changing a digit.

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 as a sum of consecutive naturals, namely, 202060010 + 202060011.

It is an arithmetic number, because the mean of its divisors is an integer number (202060011).

Almost surely, 2^404120021 is an apocalyptic number.

It is an amenable number.

404120021 is a deficient number, since it is larger than the sum of its proper divisors (1).

404120021 is an equidigital number, since it uses as much as digits as its factorization.

404120021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 404120021 is about 20102.7366544956. The cubic root of 404120021 is about 739.3273782151.

Adding to 404120021 its reverse (120021404), we get a palindrome (524141425).

It can be divided in two parts, 404 and 120021, that multiplied together give a palindrome (48488484).

The spelling of 404120021 in words is "four hundred four million, one hundred twenty thousand, twenty-one".