400399381 has 2 divisors, whose sum is σ = 400399382. Its totient is φ = 400399380.

The previous prime is 400399361. The next prime is 400399397. The reversal of 400399381 is 183993004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 291384900 + 109014481 = 17070^2 + 10441^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400399381 is a prime.

It is a super-2 number, since 2×400399381² = 320639328610366322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 400399381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400399361) 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, 200199690 + 200199691.

It is an arithmetic number, because the mean of its divisors is an integer number (200199691).

Almost surely, 2^400399381 is an apocalyptic number.

It is an amenable number.

400399381 is a deficient number, since it is larger than the sum of its proper divisors (1).

400399381 is an equidigital number, since it uses as much as digits as its factorization.

400399381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 400399381 is about 20009.9820339749. The cubic root of 400399381 is about 737.0514401898.

The spelling of 400399381 in words is "four hundred million, three hundred ninety-nine thousand, three hundred eighty-one".