20724121 has 4 divisors (see below), whose sum is σ = 22608144. Its totient is φ = 18840100.

The previous prime is 20724097. The next prime is 20724161. The reversal of 20724121 is 12142702.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20724121 - 2⁹ = 20723609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20724161) 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 3 ways as a sum of consecutive naturals, for example, 941995 + ... + 942016.

It is an arithmetic number, because the mean of its divisors is an integer number (5652036).

Almost surely, 2^20724121 is an apocalyptic number.

It is an amenable number.

20724121 is a deficient number, since it is larger than the sum of its proper divisors (1884023).

20724121 is a wasteful number, since it uses less digits than its factorization.

20724121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1884022.

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 20724121 is about 4552.3753140531. The cubic root of 20724121 is about 274.6789465386.

Adding to 20724121 its reverse (12142702), we get a palindrome (32866823).

The spelling of 20724121 in words is "twenty million, seven hundred twenty-four thousand, one hundred twenty-one".