21542311 has 6 divisors (see below), whose sum is σ = 25059480. Its totient is φ = 18464796.

The previous prime is 21542299. The next prime is 21542321. The reversal of 21542311 is 11324512.

It is not a de Polignac number, because 21542311 - 2¹⁷ = 21411239 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542321) 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 5 ways as a sum of consecutive naturals, for example, 219771 + ... + 219868.

It is an arithmetic number, because the mean of its divisors is an integer number (4176580).

Almost surely, 2^21542311 is an apocalyptic number.

21542311 is a deficient number, since it is larger than the sum of its proper divisors (3517169).

21542311 is an equidigital number, since it uses as much as digits as its factorization.

21542311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 439653 (or 439646 counting only the distinct ones).

The product of its digits is 240, while the sum is 19.

The square root of 21542311 is about 4641.3695177178. The cubic root of 21542311 is about 278.2471750567.

Adding to 21542311 its reverse (11324512), we get a palindrome (32866823).

It can be divided in two parts, 2154 and 2311, that added together give a triangular number (4465 = T₉₄).

The spelling of 21542311 in words is "twenty-one million, five hundred forty-two thousand, three hundred eleven".