120405821 has 2 divisors, whose sum is σ = 120405822. Its totient is φ = 120405820.

The previous prime is 120405811. The next prime is 120405823. The reversal of 120405821 is 128504021.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68724100 + 51681721 = 8290^2 + 7189^2 .

It is a cyclic number.

It is not a de Polignac number, because 120405821 - 2¹⁰ = 120404797 is a prime.

Together with 120405823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (120405823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60202910 + 60202911.

It is an arithmetic number, because the mean of its divisors is an integer number (60202911).

Almost surely, 2^120405821 is an apocalyptic number.

It is an amenable number.

120405821 is a deficient number, since it is larger than the sum of its proper divisors (1).

120405821 is an equidigital number, since it uses as much as digits as its factorization.

120405821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 120405821 is about 10972.9586256397. The cubic root of 120405821 is about 493.7978118311.

Adding to 120405821 its reverse (128504021), we get a palindrome (248909842).

The spelling of 120405821 in words is "one hundred twenty million, four hundred five thousand, eight hundred twenty-one".