21497199 has 4 divisors (see below), whose sum is σ = 28662936. Its totient is φ = 14331464.

The previous prime is 21497191. The next prime is 21497213. The reversal of 21497199 is 99179412.

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

It is a cyclic number.

It is not a de Polignac number, because 21497199 - 2³ = 21497191 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21497199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21497191) 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, 3582864 + ... + 3582869.

It is an arithmetic number, because the mean of its divisors is an integer number (7165734).

Almost surely, 2^21497199 is an apocalyptic number.

21497199 is a deficient number, since it is larger than the sum of its proper divisors (7165737).

21497199 is an equidigital number, since it uses as much as digits as its factorization.

21497199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7165736.

The product of its digits is 40824, while the sum is 42.

The square root of 21497199 is about 4636.5071983121. The cubic root of 21497199 is about 278.0528124566.

The spelling of 21497199 in words is "twenty-one million, four hundred ninety-seven thousand, one hundred ninety-nine".