400218989 has 2 divisors, whose sum is σ = 400218990. Its totient is φ = 400218988.

The previous prime is 400218919. The next prime is 400218991. The reversal of 400218989 is 989812004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 340697764 + 59521225 = 18458^2 + 7715^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400218989 is a prime.

Together with 400218991, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400218919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200109494 + 200109495.

It is an arithmetic number, because the mean of its divisors is an integer number (200109495).

Almost surely, 2^400218989 is an apocalyptic number.

It is an amenable number.

400218989 is a deficient number, since it is larger than the sum of its proper divisors (1).

400218989 is an equidigital number, since it uses as much as digits as its factorization.

400218989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41472, while the sum is 41.

The square root of 400218989 is about 20005.4739758897. The cubic root of 400218989 is about 736.9407355934.

The spelling of 400218989 in words is "four hundred million, two hundred eighteen thousand, nine hundred eighty-nine".