45721 has 4 divisors (see below), whose sum is σ = 49252. Its totient is φ = 42192.

The previous prime is 45707. The next prime is 45737. The reversal of 45721 is 12754.

45721 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 27225 + 18496 = 165^2 + 136^2 .

It is a cyclic number.

It is not a de Polignac number, because 45721 - 2¹³ = 37529 is a prime.

It is a Duffinian number.

45721 is a lucky number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (45751) 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, 1746 + ... + 1771.

It is an arithmetic number, because the mean of its divisors is an integer number (12313).

2⁴⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

45721 is a deficient number, since it is larger than the sum of its proper divisors (3531).

45721 is a wasteful number, since it uses less digits than its factorization.

45721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3530.

The product of its digits is 280, while the sum is 19.

The square root of 45721 is about 213.8246945514. The cubic root of 45721 is about 35.7578918793.

The spelling of 45721 in words is "forty-five thousand, seven hundred twenty-one".