21800642 has 8 divisors (see below), whose sum is σ = 34122816. Its totient is φ = 10426372.

The previous prime is 21800641. The next prime is 21800651. The reversal of 21800642 is 24600812.

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

It is a super-2 number, since 2×21800642² = 950535983224328, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is not an unprimeable number, because it can be changed into a prime (21800641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 236918 + ... + 237009.

It is an arithmetic number, because the mean of its divisors is an integer number (4265352).

Almost surely, 2^21800642 is an apocalyptic number.

21800642 is a deficient number, since it is larger than the sum of its proper divisors (12322174).

21800642 is a wasteful number, since it uses less digits than its factorization.

21800642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473952.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21800642 is about 4669.1157621117. The cubic root of 21800642 is about 279.3549863630.

The spelling of 21800642 in words is "twenty-one million, eight hundred thousand, six hundred forty-two".