20442251 has 4 divisors (see below), whose sum is σ = 20459400. Its totient is φ = 20425104.

The previous prime is 20442203. The next prime is 20442269. The reversal of 20442251 is 15224402.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15224402 = 2 ⋅7612201.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20442251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20442281) 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, 6641 + ... + 9218.

It is an arithmetic number, because the mean of its divisors is an integer number (5114850).

Almost surely, 2^20442251 is an apocalyptic number.

20442251 is a deficient number, since it is larger than the sum of its proper divisors (17149).

20442251 is a wasteful number, since it uses less digits than its factorization.

20442251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17148.

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 20442251 is about 4521.3107612727. The cubic root of 20442251 is about 273.4279494308.

Adding to 20442251 its reverse (15224402), we get a palindrome (35666653).

The spelling of 20442251 in words is "twenty million, four hundred forty-two thousand, two hundred fifty-one".