21858805 has 4 divisors (see below), whose sum is σ = 26230572. Its totient is φ = 17487040.

The previous prime is 21858803. The next prime is 21858857. The reversal of 21858805 is 50885812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5650129 + 16208676 = 2377^2 + 4026^2 .

It is not a de Polignac number, because 21858805 - 2¹ = 21858803 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21858803) 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, 2185876 + ... + 2185885.

It is an arithmetic number, because the mean of its divisors is an integer number (6557643).

Almost surely, 2^21858805 is an apocalyptic number.

It is an amenable number.

21858805 is a deficient number, since it is larger than the sum of its proper divisors (4371767).

21858805 is an equidigital number, since it uses as much as digits as its factorization.

21858805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4371766.

The product of its (nonzero) digits is 25600, while the sum is 37.

The square root of 21858805 is about 4675.3400945814. The cubic root of 21858805 is about 279.6032007004.

The spelling of 21858805 in words is "twenty-one million, eight hundred fifty-eight thousand, eight hundred five".