400638989 has 2 divisors, whose sum is σ = 400638990. Its totient is φ = 400638988.

The previous prime is 400638971. The next prime is 400639021. The reversal of 400638989 is 989836004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 388681225 + 11957764 = 19715^2 + 3458^2 .

It is a cyclic number.

It is not a de Polignac number, because 400638989 - 2²⁰ = 399590413 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400634989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200319494 + 200319495.

It is an arithmetic number, because the mean of its divisors is an integer number (200319495).

Almost surely, 2^400638989 is an apocalyptic number.

It is an amenable number.

400638989 is a deficient number, since it is larger than the sum of its proper divisors (1).

400638989 is an equidigital number, since it uses as much as digits as its factorization.

400638989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 373248, while the sum is 47.

The square root of 400638989 is about 20015.9683502947. The cubic root of 400638989 is about 737.1984335950.

The spelling of 400638989 in words is "four hundred million, six hundred thirty-eight thousand, nine hundred eighty-nine".