21197847 has 8 divisors (see below), whose sum is σ = 30833280. Its totient is φ = 12847160.

The previous prime is 21197837. The next prime is 21197851. The reversal of 21197847 is 74879112.

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

It is a cyclic number.

It is not a de Polignac number, because 21197847 - 2⁸ = 21197591 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21197837) 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, 321147 + ... + 321212.

It is an arithmetic number, because the mean of its divisors is an integer number (3854160).

Almost surely, 2^21197847 is an apocalyptic number.

21197847 is a deficient number, since it is larger than the sum of its proper divisors (9635433).

21197847 is a wasteful number, since it uses less digits than its factorization.

21197847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642373.

The product of its digits is 28224, while the sum is 39.

The square root of 21197847 is about 4604.1119664926. Note that the first 3 decimals coincide. The cubic root of 21197847 is about 276.7561312903.

The spelling of 21197847 in words is "twenty-one million, one hundred ninety-seven thousand, eight hundred forty-seven".