145240021 has 4 divisors (see below), whose sum is σ = 145295532. Its totient is φ = 145184512.

The previous prime is 145240019. The next prime is 145240037. The reversal of 145240021 is 120042541.

145240021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 131446225 + 13793796 = 11465^2 + 3714^2 .

It is a cyclic number.

It is not a de Polignac number, because 145240021 - 2¹ = 145240019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (145240321) 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, 23626 + ... + 29131.

It is an arithmetic number, because the mean of its divisors is an integer number (36323883).

Almost surely, 2^145240021 is an apocalyptic number.

It is an amenable number.

145240021 is a deficient number, since it is larger than the sum of its proper divisors (55511).

145240021 is an equidigital number, since it uses as much as digits as its factorization.

145240021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55510.

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 145240021 is about 12051.5567874030. The cubic root of 145240021 is about 525.6485059354.

Adding to 145240021 its reverse (120042541), we get a palindrome (265282562).

The spelling of 145240021 in words is "one hundred forty-five million, two hundred forty thousand, twenty-one".