401638397047821 has 12 divisors (see below), whose sum is σ = 594294213518460. Its totient is φ = 261228225721920.

The previous prime is 401638397047721. The next prime is 401638397047847. The reversal of 401638397047821 is 128740793836104.

401638397047821 is a `hidden beast` number, since 4 + 0 + 1 + 63 + 8 + 39 + 70 + 478 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 223971757450596 + 177666639597225 = 14965686^2 + 13329165^2 .

It is not a de Polignac number, because 401638397047821 - 2¹⁴ = 401638397031437 is a prime.

It is a super-2 number, since 2×401638397047821² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (401638397047891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 544225469886 + ... + 544225470623.

It is an arithmetic number, because the mean of its divisors is an integer number (49524517793205).

Almost surely, 2^{401638397047821} is an apocalyptic number.

401638397047821 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

401638397047821 is a deficient number, since it is larger than the sum of its proper divisors (192655816470639).

401638397047821 is a wasteful number, since it uses less digits than its factorization.

401638397047821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1088450940556 (or 1088450940553 counting only the distinct ones).

The product of its (nonzero) digits is 48771072, while the sum is 63.

The spelling of 401638397047821 in words is "four hundred one trillion, six hundred thirty-eight billion, three hundred ninety-seven million, forty-seven thousand, eight hundred twenty-one".