21543945 has 8 divisors (see below), whose sum is σ = 34470336. Its totient is φ = 11490096.

The previous prime is 21543931. The next prime is 21543961. The reversal of 21543945 is 54934512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21543945 - 2⁶ = 21543881 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 718117 + ... + 718146.

It is an arithmetic number, because the mean of its divisors is an integer number (4308792).

Almost surely, 2^21543945 is an apocalyptic number.

It is an amenable number.

21543945 is a deficient number, since it is larger than the sum of its proper divisors (12926391).

21543945 is a wasteful number, since it uses less digits than its factorization.

21543945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1436271.

The product of its digits is 21600, while the sum is 33.

The square root of 21543945 is about 4641.5455400114. The cubic root of 21543945 is about 278.2542099625.

The spelling of 21543945 in words is "twenty-one million, five hundred forty-three thousand, nine hundred forty-five".