21813001 has 8 divisors (see below), whose sum is σ = 24960704. Its totient is φ = 18673200.

The previous prime is 21812983. The next prime is 21813013. The reversal of 21813001 is 10031812.

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

It is not a de Polignac number, because 21813001 - 2⁷ = 21812873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21813041) 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, 6226 + ... + 9076.

It is an arithmetic number, because the mean of its divisors is an integer number (3120088).

Almost surely, 2^21813001 is an apocalyptic number.

It is an amenable number.

21813001 is a deficient number, since it is larger than the sum of its proper divisors (3147703).

21813001 is a wasteful number, since it uses less digits than its factorization.

21813001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3951.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 21813001 is about 4670.4390585897. The cubic root of 21813001 is about 279.4077660939.

Adding to 21813001 its reverse (10031812), we get a palindrome (31844813).

The spelling of 21813001 in words is "twenty-one million, eight hundred thirteen thousand, one".