400900561 has 2 divisors, whose sum is σ = 400900562. Its totient is φ = 400900560.

The previous prime is 400900559. The next prime is 400900571. The reversal of 400900561 is 165009004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 395811025 + 5089536 = 19895^2 + 2256^2 .

It is a cyclic number.

It is not a de Polignac number, because 400900561 - 2¹ = 400900559 is a prime.

It is a super-2 number, since 2×400900561² = 321442519620229442, which contains 22 as substring.

Together with 400900559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (400900571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200450280 + 200450281.

It is an arithmetic number, because the mean of its divisors is an integer number (200450281).

Almost surely, 2^400900561 is an apocalyptic number.

It is an amenable number.

400900561 is a deficient number, since it is larger than the sum of its proper divisors (1).

400900561 is an equidigital number, since it uses as much as digits as its factorization.

400900561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 400900561 is about 20022.5013672118. The cubic root of 400900561 is about 737.3588344577.

Adding to 400900561 its reverse (165009004), we get a palindrome (565909565).

The spelling of 400900561 in words is "four hundred million, nine hundred thousand, five hundred sixty-one".