400021717 has 2 divisors, whose sum is σ = 400021718. Its totient is φ = 400021716.

The previous prime is 400021693. The next prime is 400021729. The reversal of 400021717 is 717120004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 200675556 + 199346161 = 14166^2 + 14119^2 .

It is a cyclic number.

It is not a de Polignac number, because 400021717 - 2¹⁵ = 399988949 is a prime.

It is a Chen prime.

It is equal to p_21337402 and since 400021717 and 21337402 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400021757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200010858 + 200010859.

It is an arithmetic number, because the mean of its divisors is an integer number (200010859).

Almost surely, 2^400021717 is an apocalyptic number.

It is an amenable number.

400021717 is a deficient number, since it is larger than the sum of its proper divisors (1).

400021717 is an equidigital number, since it uses as much as digits as its factorization.

400021717 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 400021717 is about 20000.5429176310. The cubic root of 400021717 is about 736.8196338388.

The spelling of 400021717 in words is "four hundred million, twenty-one thousand, seven hundred seventeen".