20724571 has 4 divisors (see below), whose sum is σ = 23685232. Its totient is φ = 17763912.

The previous prime is 20724569. The next prime is 20724601. The reversal of 20724571 is 17542702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17542702 = 2 ⋅8771351.

It is a cyclic number.

It is not a de Polignac number, because 20724571 - 2¹ = 20724569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20724511) 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, 1480320 + ... + 1480333.

It is an arithmetic number, because the mean of its divisors is an integer number (5921308).

Almost surely, 2^20724571 is an apocalyptic number.

20724571 is a deficient number, since it is larger than the sum of its proper divisors (2960661).

20724571 is an equidigital number, since it uses as much as digits as its factorization.

20724571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2960660.

The product of its (nonzero) digits is 3920, while the sum is 28.

The square root of 20724571 is about 4552.4247385322. The cubic root of 20724571 is about 274.6809346347.

The spelling of 20724571 in words is "twenty million, seven hundred twenty-four thousand, five hundred seventy-one".