145120021 has 4 divisors (see below), whose sum is σ = 149801344. Its totient is φ = 140438700.

The previous prime is 145120013. The next prime is 145120049. The reversal of 145120021 is 120021541.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120021541 = 683 ⋅175727.

It is a cyclic number.

It is not a de Polignac number, because 145120021 - 2³ = 145120013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 145119977 and 145120004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (145120091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2340615 + ... + 2340676.

It is an arithmetic number, because the mean of its divisors is an integer number (37450336).

Almost surely, 2^145120021 is an apocalyptic number.

It is an amenable number.

145120021 is a deficient number, since it is larger than the sum of its proper divisors (4681323).

145120021 is an equidigital number, since it uses as much as digits as its factorization.

145120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4681322.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 145120021 is about 12046.5771487174. The cubic root of 145120021 is about 525.5036991981.

Adding to 145120021 its reverse (120021541), we get a palindrome (265141562).

The spelling of 145120021 in words is "one hundred forty-five million, one hundred twenty thousand, twenty-one".