145331521 has 4 divisors (see below), whose sum is σ = 153880452. Its totient is φ = 136782592.

The previous prime is 145331507. The next prime is 145331569. The reversal of 145331521 is 125133541.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125133541 = 13 ⋅9625657.

It can be written as a sum of positive squares in 2 ways, for example, as 129618225 + 15713296 = 11385^2 + 3964^2 .

It is a cyclic number.

It is not a de Polignac number, because 145331521 - 2⁵ = 145331489 is a prime.

It is a super-2 number, since 2×145331521² = 42242501992346882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (145331321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4274440 + ... + 4274473.

It is an arithmetic number, because the mean of its divisors is an integer number (38470113).

Almost surely, 2^145331521 is an apocalyptic number.

It is an amenable number.

145331521 is a deficient number, since it is larger than the sum of its proper divisors (8548931).

145331521 is an equidigital number, since it uses as much as digits as its factorization.

145331521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8548930.

The product of its digits is 1800, while the sum is 25.

The square root of 145331521 is about 12055.3523797523. The cubic root of 145331521 is about 525.7588674857.

The spelling of 145331521 in words is "one hundred forty-five million, three hundred thirty-one thousand, five hundred twenty-one".