721536 has 32 divisors (see below), whose sum is σ = 1917600. Its totient is φ = 240384.

The previous prime is 721529. The next prime is 721547. The reversal of 721536 is 635127.

It is a tau number, because it is divible by the number of its divisors (32).

It is a super-2 number, since 2×721536² = 1041228398592, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721536.

It is an unprimeable number.

721536 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 556 + ... + 1323.

It is an arithmetic number, because the mean of its divisors is an integer number (59925).

2⁷²¹⁵³⁶ is an apocalyptic number.

It is an amenable number.

721536 is an abundant number, since it is smaller than the sum of its proper divisors (1196064).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721536 is a wasteful number, since it uses less digits than its factorization.

721536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1896 (or 1884 counting only the distinct ones).

The product of its digits is 1260, while the sum is 24.

The square root of 721536 is about 849.4327518998. The cubic root of 721536 is about 89.6917851959.

It can be divided in two parts, 72 and 1536, that multiplied together give a cube (110592 = 48³).

The spelling of 721536 in words is "seven hundred twenty-one thousand, five hundred thirty-six".