153721 has 4 divisors (see below), whose sum is σ = 154512. Its totient is φ = 152932.

The previous prime is 153719. The next prime is 153733. The reversal of 153721 is 127351.

153721 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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 153721 - 2¹ = 153719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (153701) 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, 126 + ... + 568.

It is an arithmetic number, because the mean of its divisors is an integer number (38628).

2¹⁵³⁷²¹ is an apocalyptic number.

It is an amenable number.

153721 is a deficient number, since it is larger than the sum of its proper divisors (791).

153721 is an equidigital number, since it uses as much as digits as its factorization.

153721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 790.

The product of its digits is 210, while the sum is 19.

The square root of 153721 is about 392.0726973407. The cubic root of 153721 is about 53.5686950563.

The spelling of 153721 in words is "one hundred fifty-three thousand, seven hundred twenty-one".