400031221021 has 4 divisors (see below), whose sum is σ = 400456334844. Its totient is φ = 399606107200.

The previous prime is 400031221019. The next prime is 400031221039. The reversal of 400031221021 is 120122130004.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 344027998521 + 56003222500 = 586539^2 + 236650^2 .

It is a cyclic number.

It is not a de Polignac number, because 400031221021 - 2¹ = 400031221019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 400031220986 and 400031221004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400031221001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 212555500 + ... + 212557381.

It is an arithmetic number, because the mean of its divisors is an integer number (100114083711).

Almost surely, 2^400031221021 is an apocalyptic number.

It is an amenable number.

400031221021 is a deficient number, since it is larger than the sum of its proper divisors (425113823).

400031221021 is an equidigital number, since it uses as much as digits as its factorization.

400031221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425113822.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 400031221021 its reverse (120122130004), we get a palindrome (520153351025).

The spelling of 400031221021 in words is "four hundred billion, thirty-one million, two hundred twenty-one thousand, twenty-one".