21047847 has 4 divisors (see below), whose sum is σ = 28063800. Its totient is φ = 14031896.

The previous prime is 21047833. The next prime is 21047861. The reversal of 21047847 is 74874012.

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 (21047833) and next prime (21047861).

It is a cyclic number.

It is not a de Polignac number, because 21047847 - 2¹⁴ = 21031463 is a prime.

It is a super-3 number, since 3×21047847³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21047827) 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, 3507972 + ... + 3507977.

It is an arithmetic number, because the mean of its divisors is an integer number (7015950).

Almost surely, 2^21047847 is an apocalyptic number.

21047847 is a deficient number, since it is larger than the sum of its proper divisors (7015953).

21047847 is an equidigital number, since it uses as much as digits as its factorization.

21047847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7015952.

The product of its (nonzero) digits is 12544, while the sum is 33.

The square root of 21047847 is about 4587.7932603813. The cubic root of 21047847 is about 276.1017924257.

The spelling of 21047847 in words is "twenty-one million, forty-seven thousand, eight hundred forty-seven".