21543518 has 16 divisors (see below), whose sum is σ = 32970240. Its totient is φ = 10555776.

The previous prime is 21543503. The next prime is 21543527. The reversal of 21543518 is 81534512.

It is a congruent number.

It is an unprimeable number.

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, 22130 + ... + 23082.

It is an arithmetic number, because the mean of its divisors is an integer number (2060640).

Almost surely, 2^21543518 is an apocalyptic number.

21543518 is a deficient number, since it is larger than the sum of its proper divisors (11426722).

21543518 is a wasteful number, since it uses less digits than its factorization.

21543518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1171.

The product of its digits is 4800, while the sum is 29.

The square root of 21543518 is about 4641.4995421738. The cubic root of 21543518 is about 278.2523716218.

The spelling of 21543518 in words is "twenty-one million, five hundred forty-three thousand, five hundred eighteen".