21293847 has 12 divisors (see below), whose sum is σ = 31897320. Its totient is φ = 14195736.

The previous prime is 21293803. The next prime is 21293861. The reversal of 21293847 is 74839212.

It is a de Polignac number, because none of the positive numbers 2^k-21293847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21293887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43572 + ... + 44057.

It is an arithmetic number, because the mean of its divisors is an integer number (2658110).

Almost surely, 2^21293847 is an apocalyptic number.

21293847 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21293847 is a deficient number, since it is larger than the sum of its proper divisors (10603473).

21293847 is an frugal number, since it uses more digits than its factorization.

21293847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87644 (or 87632 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21293847 is about 4614.5256527622. The cubic root of 21293847 is about 277.1732897185.

The spelling of 21293847 in words is "twenty-one million, two hundred ninety-three thousand, eight hundred forty-seven".