21543401 has 8 divisors (see below), whose sum is σ = 23735808. Its totient is φ = 19390000.

The previous prime is 21543373. The next prime is 21543407. The reversal of 21543401 is 10434512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21543401 - 2¹⁰ = 21542377 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21543407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8585 + ... + 10806.

It is an arithmetic number, because the mean of its divisors is an integer number (2966976).

Almost surely, 2^21543401 is an apocalyptic number.

It is an amenable number.

21543401 is a deficient number, since it is larger than the sum of its proper divisors (2192407).

21543401 is a wasteful number, since it uses less digits than its factorization.

21543401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19503.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21543401 is about 4641.4869384713. The cubic root of 21543401 is about 278.2518679036.

Adding to 21543401 its reverse (10434512), we get a palindrome (31977913).

Subtracting from 21543401 its reverse (10434512), we obtain a square (11108889 = 3333²).

It can be divided in two parts, 2154 and 3401, that added together give a palindrome (5555).

The spelling of 21543401 in words is "twenty-one million, five hundred forty-three thousand, four hundred one".