407216021 has 2 divisors, whose sum is σ = 407216022. Its totient is φ = 407216020.

The previous prime is 407216009. The next prime is 407216023. The reversal of 407216021 is 120612704.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 403567921 + 3648100 = 20089^2 + 1910^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-407216021 is a prime.

It is a Sophie Germain prime.

Together with 407216023, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (407216023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 203608010 + 203608011.

It is an arithmetic number, because the mean of its divisors is an integer number (203608011).

Almost surely, 2^407216021 is an apocalyptic number.

It is an amenable number.

407216021 is a deficient number, since it is larger than the sum of its proper divisors (1).

407216021 is an equidigital number, since it uses as much as digits as its factorization.

407216021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 407216021 is about 20179.5941733227. The cubic root of 407216021 is about 741.2105951580.

Adding to 407216021 its reverse (120612704), we get a palindrome (527828725).

The spelling of 407216021 in words is "four hundred seven million, two hundred sixteen thousand, twenty-one".