21297899 has 16 divisors (see below), whose sum is σ = 25651200. Its totient is φ = 17657640.

The previous prime is 21297869. The next prime is 21297907. The reversal of 21297899 is 99879212.

It is a happy number.

It is not a de Polignac number, because 21297899 - 2¹² = 21293803 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 (21297869) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9632 + ... + 11634.

It is an arithmetic number, because the mean of its divisors is an integer number (1603200).

Almost surely, 2^21297899 is an apocalyptic number.

21297899 is a deficient number, since it is larger than the sum of its proper divisors (4353301).

21297899 is an equidigital number, since it uses as much as digits as its factorization.

21297899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2055 (or 2041 counting only the distinct ones).

The product of its digits is 163296, while the sum is 47.

The square root of 21297899 is about 4614.9646802549. The cubic root of 21297899 is about 277.1908696785.

The spelling of 21297899 in words is "twenty-one million, two hundred ninety-seven thousand, eight hundred ninety-nine".