20708647 has 4 divisors (see below), whose sum is σ = 20718720. Its totient is φ = 20698576.

The previous prime is 20708599. The next prime is 20708663. The reversal of 20708647 is 74680702.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 74680702 = 2 ⋅37340351.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20708647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20708447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 718 + ... + 6475.

It is an arithmetic number, because the mean of its divisors is an integer number (5179680).

Almost surely, 2^20708647 is an apocalyptic number.

20708647 is a deficient number, since it is larger than the sum of its proper divisors (10073).

20708647 is an equidigital number, since it uses as much as digits as its factorization.

20708647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10072.

The product of its (nonzero) digits is 18816, while the sum is 34.

The square root of 20708647 is about 4550.6754443709. The cubic root of 20708647 is about 274.6105650243.

It can be divided in two parts, 20708 and 647, that multiplied together give a triangular number (13398076 = T₅₁₇₆).

The spelling of 20708647 in words is "twenty million, seven hundred eight thousand, six hundred forty-seven".