42240120021 has 18 divisors (see below), whose sum is σ = 67064434710. Its totient is φ = 25600072080.

The previous prime is 42240120019. The next prime is 42240120023. The reversal of 42240120021 is 12002104224.

42240120021 is a `hidden beast` number, since 42 + 2 + 401 + 200 + 21 = 666.

It is an interprime number because it is at equal distance from previous prime (42240120019) and next prime (42240120023).

It can be written as a sum of positive squares in only one way, i.e., 42091035921 + 149084100 = 205161^2 + 12210^2 .

It is not a de Polignac number, because 42240120021 - 2¹ = 42240120019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 42240119976 and 42240120003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42240120023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 19392906 + ... + 19395083.

Almost surely, 2^42240120021 is an apocalyptic number.

It is an amenable number.

42240120021 is a deficient number, since it is larger than the sum of its proper divisors (24824314689).

42240120021 is a wasteful number, since it uses less digits than its factorization.

42240120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38788017 (or 38788003 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

Adding to 42240120021 its reverse (12002104224), we get a palindrome (54242224245).

It can be divided in two parts, 42240 and 120021, that added together give a palindrome (162261).

The spelling of 42240120021 in words is "forty-two billion, two hundred forty million, one hundred twenty thousand, twenty-one".