145215821 has 4 divisors (see below), whose sum is σ = 145370112. Its totient is φ = 145061532.

The previous prime is 145215817. The next prime is 145215827. The reversal of 145215821 is 128512541.

145215821 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 145215821 - 2² = 145215817 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 (145215827) 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, 75725 + ... + 77618.

It is an arithmetic number, because the mean of its divisors is an integer number (36342528).

Almost surely, 2^145215821 is an apocalyptic number.

It is an amenable number.

145215821 is a deficient number, since it is larger than the sum of its proper divisors (154291).

145215821 is an equidigital number, since it uses as much as digits as its factorization.

145215821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154290.

The product of its digits is 3200, while the sum is 29.

The square root of 145215821 is about 12050.5527259126. The cubic root of 145215821 is about 525.6193096658.

The spelling of 145215821 in words is "one hundred forty-five million, two hundred fifteen thousand, eight hundred twenty-one".