21198247 has 4 divisors (see below), whose sum is σ = 24226576. Its totient is φ = 18169920.

The previous prime is 21198241. The next prime is 21198253. The reversal of 21198247 is 74289112.

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

It is an interprime number because it is at equal distance from previous prime (21198241) and next prime (21198253).

It is a cyclic number.

It is not a de Polignac number, because 21198247 - 2³ = 21198239 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 (21198241) 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, 1514154 + ... + 1514167.

It is an arithmetic number, because the mean of its divisors is an integer number (6056644).

Almost surely, 2^21198247 is an apocalyptic number.

21198247 is a deficient number, since it is larger than the sum of its proper divisors (3028329).

21198247 is an equidigital number, since it uses as much as digits as its factorization.

21198247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3028328.

The product of its digits is 8064, while the sum is 34.

The square root of 21198247 is about 4604.1554057178. The cubic root of 21198247 is about 276.7578720607.

The spelling of 21198247 in words is "twenty-one million, one hundred ninety-eight thousand, two hundred forty-seven".