721528 has 8 divisors (see below), whose sum is σ = 1352880. Its totient is φ = 360760.

The previous prime is 721499. The next prime is 721529. The reversal of 721528 is 825127.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721529) by changing a digit.

721528 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45088 + ... + 45103.

It is an arithmetic number, because the mean of its divisors is an integer number (169110).

2⁷²¹⁵²⁸ is an apocalyptic number.

It is an amenable number.

721528 is a deficient number, since it is larger than the sum of its proper divisors (631352).

721528 is a wasteful number, since it uses less digits than its factorization.

721528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90197 (or 90193 counting only the distinct ones).

The product of its digits is 1120, while the sum is 25.

The square root of 721528 is about 849.4280428618. The cubic root of 721528 is about 89.6914537101.

It can be divided in two parts, 72 and 1528, that added together give a square (1600 = 40²).

The spelling of 721528 in words is "seven hundred twenty-one thousand, five hundred twenty-eight".