400221221 has 2 divisors, whose sum is σ = 400221222. Its totient is φ = 400221220.

The previous prime is 400221197. The next prime is 400221223. The reversal of 400221221 is 122122004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 360468196 + 39753025 = 18986^2 + 6305^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400221221 is a prime.

It is a Sophie Germain prime.

Together with 400221223, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 400221196 and 400221205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400221223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200110610 + 200110611.

It is an arithmetic number, because the mean of its divisors is an integer number (200110611).

Almost surely, 2^400221221 is an apocalyptic number.

It is an amenable number.

400221221 is a deficient number, since it is larger than the sum of its proper divisors (1).

400221221 is an equidigital number, since it uses as much as digits as its factorization.

400221221 is an evil number, because the sum of its binary digits is even.

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

The square root of 400221221 is about 20005.5297605437. The cubic root of 400221221 is about 736.9421055506.

Adding to 400221221 its reverse (122122004), we get a palindrome (522343225).

The spelling of 400221221 in words is "four hundred million, two hundred twenty-one thousand, two hundred twenty-one".