21855745 has 8 divisors (see below), whose sum is σ = 26559360. Its totient is φ = 17262960.

The previous prime is 21855737. The next prime is 21855781. The reversal of 21855745 is 54755812.

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

It is not a de Polignac number, because 21855745 - 2³ = 21855737 is a prime.

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, 27271 + ... + 28060.

It is an arithmetic number, because the mean of its divisors is an integer number (3319920).

Almost surely, 2^21855745 is an apocalyptic number.

It is an amenable number.

21855745 is a deficient number, since it is larger than the sum of its proper divisors (4703615).

21855745 is an equidigital number, since it uses as much as digits as its factorization.

21855745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55415.

The product of its digits is 56000, while the sum is 37.

The square root of 21855745 is about 4675.0128342070. The cubic root of 21855745 is about 279.5901529344.

The spelling of 21855745 in words is "twenty-one million, eight hundred fifty-five thousand, seven hundred forty-five".