42551 has 4 divisors (see below), whose sum is σ = 45072. Its totient is φ = 40032.

The previous prime is 42533. The next prime is 42557. The reversal of 42551 is 15524.

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

It is a cyclic number.

It is not a de Polignac number, because 42551 - 2⁶ = 42487 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 2503 = 42551 / (4 + 2 + 5 + 5 + 1).

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 42551.

It is not an unprimeable number, because it can be changed into a prime (42557) 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, 1235 + ... + 1268.

It is an arithmetic number, because the mean of its divisors is an integer number (11268).

2⁴²⁵⁵¹ is an apocalyptic number.

42551 is a deficient number, since it is larger than the sum of its proper divisors (2521).

42551 is a wasteful number, since it uses less digits than its factorization.

42551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2520.

The product of its digits is 200, while the sum is 17.

The square root of 42551 is about 206.2789373639. The cubic root of 42551 is about 34.9116137187.

The spelling of 42551 in words is "forty-two thousand, five hundred fifty-one".