400203021 has 16 divisors (see below), whose sum is σ = 547384640. Its totient is φ = 259943040.

The previous prime is 400203017. The next prime is 400203029. The reversal of 400203021 is 120302004.

It is not a de Polignac number, because 400203021 - 2² = 400203017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 400202988 and 400203006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400203029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50625 + ... + 57993.

It is an arithmetic number, because the mean of its divisors is an integer number (34211540).

Almost surely, 2^400203021 is an apocalyptic number.

It is an amenable number.

400203021 is a deficient number, since it is larger than the sum of its proper divisors (147181619).

400203021 is a wasteful number, since it uses less digits than its factorization.

400203021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7836.

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 400203021 is about 20005.0748811395. The cubic root of 400203021 is about 736.9309346040.

Adding to 400203021 its reverse (120302004), we get a palindrome (520505025).

The spelling of 400203021 in words is "four hundred million, two hundred three thousand, twenty-one".