145721 has 2 divisors, whose sum is σ = 145722. Its totient is φ = 145720.

The previous prime is 145709. The next prime is 145723. The reversal of 145721 is 127541.

145721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 132496 + 13225 = 364^2 + 115^2 .

It is an emirp because it is prime and its reverse (127541) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-145721 is a prime.

It is a Sophie Germain prime.

Together with 145723, it forms a pair of twin primes.

It is a Chen prime.

It is an Ulam number.

It is a Curzon number.

It is equal to p₁₃₄₈₄ and since 145721 and 13484 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 145693 and 145702.

It is not a weakly prime, because it can be changed into another prime (145723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 72860 + 72861.

It is an arithmetic number, because the mean of its divisors is an integer number (72861).

2¹⁴⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

145721 is a deficient number, since it is larger than the sum of its proper divisors (1).

145721 is an equidigital number, since it uses as much as digits as its factorization.

145721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 280, while the sum is 20.

The square root of 145721 is about 381.7342007209. The cubic root of 145721 is about 52.6228115045.

The spelling of 145721 in words is "one hundred forty-five thousand, seven hundred twenty-one".