21245847 has 16 divisors (see below), whose sum is σ = 32820480. Its totient is φ = 11973312.

The previous prime is 21245843. The next prime is 21245849. The reversal of 21245847 is 74854212.

It is not a de Polignac number, because 21245847 - 2² = 21245843 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245843) 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 15 ways as a sum of consecutive naturals, for example, 5397 + ... + 8462.

It is an arithmetic number, because the mean of its divisors is an integer number (2051280).

Almost surely, 2^21245847 is an apocalyptic number.

21245847 is a deficient number, since it is larger than the sum of its proper divisors (11574633).

21245847 is a wasteful number, since it uses less digits than its factorization.

21245847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13942.

The product of its digits is 17920, while the sum is 33.

The square root of 21245847 is about 4609.3217505399. The cubic root of 21245847 is about 276.9648675831.

The spelling of 21245847 in words is "twenty-one million, two hundred forty-five thousand, eight hundred forty-seven".