21855793 has 4 divisors (see below), whose sum is σ = 21913840. Its totient is φ = 21797748.

The previous prime is 21855781. The next prime is 21855803. The reversal of 21855793 is 39755812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21855793 - 2¹⁷ = 21724721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21855293) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28455 + ... + 29212.

It is an arithmetic number, because the mean of its divisors is an integer number (5478460).

Almost surely, 2^21855793 is an apocalyptic number.

It is an amenable number.

21855793 is a deficient number, since it is larger than the sum of its proper divisors (58047).

21855793 is an equidigital number, since it uses as much as digits as its factorization.

21855793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58046.

The product of its digits is 75600, while the sum is 40.

The square root of 21855793 is about 4675.0179678799. The cubic root of 21855793 is about 279.5903576146.

The spelling of 21855793 in words is "twenty-one million, eight hundred fifty-five thousand, seven hundred ninety-three".