42320021 has 4 divisors (see below), whose sum is σ = 44809452. Its totient is φ = 39830592.

The previous prime is 42320009. The next prime is 42320029. The reversal of 42320021 is 12002324.

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 18447025 + 23872996 = 4295^2 + 4886^2 .

It is not a de Polignac number, because 42320021 - 2¹⁸ = 42057877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42319978 and 42320005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42320029) 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, 1244690 + ... + 1244723.

It is an arithmetic number, because the mean of its divisors is an integer number (11202363).

Almost surely, 2^42320021 is an apocalyptic number.

It is an amenable number.

42320021 is a deficient number, since it is larger than the sum of its proper divisors (2489431).

42320021 is a wasteful number, since it uses less digits than its factorization.

42320021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2489430.

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 42320021 is about 6505.3840009641. The cubic root of 42320021 is about 348.4832899571.

Adding to 42320021 its reverse (12002324), we get a palindrome (54322345).

The spelling of 42320021 in words is "forty-two million, three hundred twenty thousand, twenty-one".