20520847 has 4 divisors (see below), whose sum is σ = 20998120. Its totient is φ = 20043576.

The previous prime is 20520833. The next prime is 20520859. The reversal of 20520847 is 74802502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20520847 is a prime.

It is a super-2 number, since 2×20520847² = 842210323194818, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20521847) 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, 238572 + ... + 238657.

It is an arithmetic number, because the mean of its divisors is an integer number (5249530).

Almost surely, 2^20520847 is an apocalyptic number.

20520847 is a deficient number, since it is larger than the sum of its proper divisors (477273).

20520847 is an equidigital number, since it uses as much as digits as its factorization.

20520847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 477272.

The product of its (nonzero) digits is 4480, while the sum is 28.

The square root of 20520847 is about 4529.9941501066. The cubic root of 20520847 is about 273.7779249121. Note that the first 3 decimals are identical.

The spelling of 20520847 in words is "twenty million, five hundred twenty thousand, eight hundred forty-seven".