21043542401 has 12 divisors (see below), whose sum is σ = 25048509552. Its totient is φ = 17617847688.

The previous prime is 21043542389. The next prime is 21043542413. The reversal of 21043542401 is 10424534012.

It is an interprime number because it is at equal distance from previous prime (21043542389) and next prime (21043542413).

It is not a de Polignac number, because 21043542401 - 2¹⁸ = 21043280257 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21043542451) 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 11 ways as a sum of consecutive naturals, for example, 4991615 + ... + 4995828.

It is an arithmetic number, because the mean of its divisors is an integer number (2087375796).

Almost surely, 2^21043542401 is an apocalyptic number.

It is an amenable number.

21043542401 is a deficient number, since it is larger than the sum of its proper divisors (4004967151).

21043542401 is an equidigital number, since it uses as much as digits as its factorization.

21043542401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9987500 (or 9987493 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 26.

The spelling of 21043542401 in words is "twenty-one billion, forty-three million, five hundred forty-two thousand, four hundred one".