400540221 has 20 divisors (see below), whose sum is σ = 599323164. Its totient is φ = 266587200.

The previous prime is 400540219. The next prime is 400540241. The reversal of 400540221 is 122045004.

400540221 is a `hidden beast` number, since 400 + 5 + 40 + 221 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 333464121 + 67076100 = 18261^2 + 8190^2 .

It is not a de Polignac number, because 400540221 - 2¹ = 400540219 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 400540194 and 400540203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400540201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 49801 + ... + 57281.

Almost surely, 2^400540221 is an apocalyptic number.

It is an amenable number.

400540221 is a deficient number, since it is larger than the sum of its proper divisors (198782943).

400540221 is an equidigital number, since it uses as much as digits as its factorization.

400540221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8154 (or 8145 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 400540221 is about 20013.5009680965. The cubic root of 400540221 is about 737.1378490446.

Adding to 400540221 its reverse (122045004), we get a palindrome (522585225).

The spelling of 400540221 in words is "four hundred million, five hundred forty thousand, two hundred twenty-one".