21001199 has 4 divisors (see below), whose sum is σ = 21012936. Its totient is φ = 20989464.

The previous prime is 21001187. The next prime is 21001247. The reversal of 21001199 is 99110012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21001199 - 2¹² = 20997103 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 (21001399) 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, 2564 + ... + 6969.

It is an arithmetic number, because the mean of its divisors is an integer number (5253234).

Almost surely, 2^21001199 is an apocalyptic number.

21001199 is a deficient number, since it is larger than the sum of its proper divisors (11737).

21001199 is an equidigital number, since it uses as much as digits as its factorization.

21001199 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11736.

The product of its (nonzero) digits is 162, while the sum is 23.

The square root of 21001199 is about 4582.7065147138. The cubic root of 21001199 is about 275.8976682526.

The spelling of 21001199 in words is "twenty-one million, one thousand, one hundred ninety-nine".