20724401 has 4 divisors (see below), whose sum is σ = 20875812. Its totient is φ = 20572992.

The previous prime is 20724397. The next prime is 20724427. The reversal of 20724401 is 10442702.

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

It can be written as a sum of positive squares in 2 ways, for example, as 17305600 + 3418801 = 4160^2 + 1849^2 .

It is a cyclic number.

It is not a de Polignac number, because 20724401 - 2² = 20724397 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20724491) 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, 75500 + ... + 75773.

It is an arithmetic number, because the mean of its divisors is an integer number (5218953).

Almost surely, 2^20724401 is an apocalyptic number.

It is an amenable number.

20724401 is a deficient number, since it is larger than the sum of its proper divisors (151411).

20724401 is a wasteful number, since it uses less digits than its factorization.

20724401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151410.

The product of its (nonzero) digits is 448, while the sum is 20.

The square root of 20724401 is about 4552.4060671254. The cubic root of 20724401 is about 274.6801835796.

The spelling of 20724401 in words is "twenty million, seven hundred twenty-four thousand, four hundred one".