21543140 has 24 divisors (see below), whose sum is σ = 46701312. Its totient is φ = 8339040.

The previous prime is 21543133. The next prime is 21543173. The reversal of 21543140 is 4134512.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16754 + ... + 17993.

It is an arithmetic number, because the mean of its divisors is an integer number (1945888).

Almost surely, 2^21543140 is an apocalyptic number.

21543140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21543140 is an abundant number, since it is smaller than the sum of its proper divisors (25158172).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21543140 is a wasteful number, since it uses less digits than its factorization.

21543140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34787 (or 34785 counting only the distinct ones).

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

The square root of 21543140 is about 4641.4588223963. The cubic root of 21543140 is about 278.2507442180.

Adding to 21543140 its reverse (4134512), we get a palindrome (25677652).

The spelling of 21543140 in words is "twenty-one million, five hundred forty-three thousand, one hundred forty".