400401591581 has 2 divisors, whose sum is σ = 400401591582. Its totient is φ = 400401591580.

The previous prime is 400401591533. The next prime is 400401591589. The reversal of 400401591581 is 185195104004.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 400004386681 + 397204900 = 632459^2 + 19930^2 .

It is a cyclic number.

It is not a de Polignac number, because 400401591581 - 2³⁰ = 399327849757 is a prime.

It is a super-2 number, since 2×400401591581² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400401591589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200200795790 + 200200795791.

It is an arithmetic number, because the mean of its divisors is an integer number (200200795791).

Almost surely, 2^400401591581 is an apocalyptic number.

It is an amenable number.

400401591581 is a deficient number, since it is larger than the sum of its proper divisors (1).

400401591581 is an equidigital number, since it uses as much as digits as its factorization.

400401591581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28800, while the sum is 38.

Adding to 400401591581 its reverse (185195104004), we get a palindrome (585596695585).

The spelling of 400401591581 in words is "four hundred billion, four hundred one million, five hundred ninety-one thousand, five hundred eighty-one".