20847421 has 8 divisors (see below), whose sum is σ = 24216704. Its totient is φ = 17575920.

The previous prime is 20847419. The next prime is 20847443. The reversal of 20847421 is 12474802.

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 20847421 - 2¹ = 20847419 is a prime.

It is a super-2 number, since 2×20847421² = 869229924702482, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20847421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20847401) 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, 23985 + ... + 24838.

It is an arithmetic number, because the mean of its divisors is an integer number (3027088).

Almost surely, 2^20847421 is an apocalyptic number.

It is an amenable number.

20847421 is a deficient number, since it is larger than the sum of its proper divisors (3369283).

20847421 is an equidigital number, since it uses as much as digits as its factorization.

20847421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48891.

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 20847421 is about 4565.8976116422. The cubic root of 20847421 is about 275.2226120338. Note that the first 3 decimals are identical.

The spelling of 20847421 in words is "twenty million, eight hundred forty-seven thousand, four hundred twenty-one".