721976 has 8 divisors (see below), whose sum is σ = 1353720. Its totient is φ = 360984.

The previous prime is 721961. The next prime is 721979. The reversal of 721976 is 679127.

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 (721979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45116 + ... + 45131.

It is an arithmetic number, because the mean of its divisors is an integer number (169215).

2⁷²¹⁹⁷⁶ is an apocalyptic number.

It is an amenable number.

721976 is a deficient number, since it is larger than the sum of its proper divisors (631744).

721976 is a wasteful number, since it uses less digits than its factorization.

721976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90253 (or 90249 counting only the distinct ones).

The product of its digits is 5292, while the sum is 32.

The square root of 721976 is about 849.6917087980. The cubic root of 721976 is about 89.7100131459.

Subtracting from 721976 its reverse (679127), we obtain a square (42849 = 207²).

It can be divided in two parts, 72 and 1976, that added together give a 11-th power (2048 = 2¹¹).

The spelling of 721976 in words is "seven hundred twenty-one thousand, nine hundred seventy-six".