721145 has 8 divisors (see below), whose sum is σ = 911040. Its totient is φ = 546480.

The previous prime is 721141. The next prime is 721159. The reversal of 721145 is 541127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 721145 - 2² = 721141 is a prime.

It is a super-2 number, since 2×721145² = 1040100222050, which contains 22 as substring.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721145.

It is not an unprimeable number, because it can be changed into a prime (721141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3701 + ... + 3890.

It is an arithmetic number, because the mean of its divisors is an integer number (113880).

2⁷²¹¹⁴⁵ is an apocalyptic number.

It is an amenable number.

721145 is a deficient number, since it is larger than the sum of its proper divisors (189895).

721145 is a wasteful number, since it uses less digits than its factorization.

721145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7615.

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

The square root of 721145 is about 849.2025671181. The cubic root of 721145 is about 89.6755809573.

The spelling of 721145 in words is "seven hundred twenty-one thousand, one hundred forty-five".