21800001 has 8 divisors (see below), whose sum is σ = 30776544. Its totient is φ = 13678400.

The previous prime is 21799979. The next prime is 21800003. The reversal of 21800001 is 10000812.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21800001 - 2⁶ = 21799937 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21800001.

It is not an unprimeable number, because it can be changed into a prime (21800003) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 213675 + ... + 213776.

It is an arithmetic number, because the mean of its divisors is an integer number (3847068).

Almost surely, 2^21800001 is an apocalyptic number.

It is an amenable number.

21800001 is a deficient number, since it is larger than the sum of its proper divisors (8976543).

21800001 is a wasteful number, since it uses less digits than its factorization.

21800001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 427471.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 21800001 is about 4669.0471190597. The cubic root of 21800001 is about 279.3522483962.

Adding to 21800001 its reverse (10000812), we get a palindrome (31800813).

The spelling of 21800001 in words is "twenty-one million, eight hundred thousand, one".