400021201521 has 12 divisors (see below), whose sum is σ = 611797131972. Its totient is φ = 250993694976.

The previous prime is 400021201507. The next prime is 400021201523. The reversal of 400021201521 is 125102120004.

400021201521 is a `hidden beast` number, since 400 + 0 + 212 + 0 + 1 + 52 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 325019711025 + 75001490496 = 570105^2 + 273864^2 .

It is not a de Polignac number, because 400021201521 - 2¹⁸ = 400020939377 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 400021201494 and 400021201503.

It is not an unprimeable number, because it can be changed into a prime (400021201523) 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 11 ways as a sum of consecutive naturals, for example, 1307258676 + ... + 1307258981.

It is an arithmetic number, because the mean of its divisors is an integer number (50983094331).

Almost surely, 2^400021201521 is an apocalyptic number.

It is an amenable number.

400021201521 is a deficient number, since it is larger than the sum of its proper divisors (211775930451).

400021201521 is a wasteful number, since it uses less digits than its factorization.

400021201521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2614517680 (or 2614517677 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

Adding to 400021201521 its reverse (125102120004), we get a palindrome (525123321525).

The spelling of 400021201521 in words is "four hundred billion, twenty-one million, two hundred one thousand, five hundred twenty-one".