21540843 has 16 divisors (see below), whose sum is σ = 32516640. Its totient is φ = 14088672.

The previous prime is 21540833. The next prime is 21540847. The reversal of 21540843 is 34804512.

21540843 is a `hidden beast` number, since 215 + 408 + 43 = 666.

It is not a de Polignac number, because 21540843 - 2⁸ = 21540587 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21540847) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6096 + ... + 8957.

It is an arithmetic number, because the mean of its divisors is an integer number (2032290).

Almost surely, 2^21540843 is an apocalyptic number.

21540843 is a deficient number, since it is larger than the sum of its proper divisors (10975797).

21540843 is a wasteful number, since it uses less digits than its factorization.

21540843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15115 (or 15109 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 21540843 is about 4641.2113720450. The cubic root of 21540843 is about 278.2408545319.

The spelling of 21540843 in words is "twenty-one million, five hundred forty thousand, eight hundred forty-three".