400221509 has 2 divisors, whose sum is σ = 400221510. Its totient is φ = 400221508.

The previous prime is 400221473. The next prime is 400221517. The reversal of 400221509 is 905122004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 359860900 + 40360609 = 18970^2 + 6353^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400221509 is a prime.

It is a Sophie Germain 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 (400221539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200110754 + 200110755.

It is an arithmetic number, because the mean of its divisors is an integer number (200110755).

Almost surely, 2^400221509 is an apocalyptic number.

It is an amenable number.

400221509 is a deficient number, since it is larger than the sum of its proper divisors (1).

400221509 is an equidigital number, since it uses as much as digits as its factorization.

400221509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 400221509 is about 20005.5369585522. The cubic root of 400221509 is about 736.9422823189.

The spelling of 400221509 in words is "four hundred million, two hundred twenty-one thousand, five hundred nine".