21542431 has 8 divisors (see below), whose sum is σ = 21902400. Its totient is φ = 21184800.

The previous prime is 21542413. The next prime is 21542453. The reversal of 21542431 is 13424512.

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 21542431 - 2¹¹ = 21540383 is a prime.

It is a super-2 number, since 2×21542431² = 928152666779522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542231) 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, 30381 + ... + 31081.

It is an arithmetic number, because the mean of its divisors is an integer number (2737800).

Almost surely, 2^21542431 is an apocalyptic number.

21542431 is a deficient number, since it is larger than the sum of its proper divisors (359969).

21542431 is an equidigital number, since it uses as much as digits as its factorization.

21542431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1169.

The product of its digits is 960, while the sum is 22.

The square root of 21542431 is about 4641.3824449188. The cubic root of 21542431 is about 278.2476917081.

Adding to 21542431 its reverse (13424512), we get a palindrome (34966943).

The spelling of 21542431 in words is "twenty-one million, five hundred forty-two thousand, four hundred thirty-one".