400681 has 2 divisors, whose sum is σ = 400682. Its totient is φ = 400680.

The previous prime is 400679. The next prime is 400703. The reversal of 400681 is 186004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 354025 + 46656 = 595^2 + 216^2 .

It is a cyclic number.

It is not a de Polignac number, because 400681 - 2¹ = 400679 is a prime.

It is a super-2 number, since 2×400681² = 321090527522, which contains 22 as substring.

Together with 400679, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (400601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200340 + 200341.

It is an arithmetic number, because the mean of its divisors is an integer number (200341).

2⁴⁰⁰⁶⁸¹ is an apocalyptic number.

It is an amenable number.

400681 is a deficient number, since it is larger than the sum of its proper divisors (1).

400681 is an equidigital number, since it uses as much as digits as its factorization.

400681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 400681 is about 632.9936808531. The cubic root of 400681 is about 73.7224200234.

Adding to 400681 its reverse (186004), we get a palindrome (586685).

It can be divided in two parts, 400 and 681, that added together give a triangular number (1081 = T₄₆).

The spelling of 400681 in words is "four hundred thousand, six hundred eighty-one".