721749765 has 32 divisors (see below), whose sum is σ = 1265812992. Its totient is φ = 348264000.

The previous prime is 721749731. The next prime is 721749779. The reversal of 721749765 is 567947127.

It is a happy number.

It is not a de Polignac number, because 721749765 - 2¹⁷ = 721618693 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24450 + ... + 45180.

It is an arithmetic number, because the mean of its divisors is an integer number (39556656).

Almost surely, 2^721749765 is an apocalyptic number.

It is an amenable number.

721749765 is a deficient number, since it is larger than the sum of its proper divisors (544063227).

721749765 is a wasteful number, since it uses less digits than its factorization.

721749765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20961.

The product of its digits is 740880, while the sum is 48.

The square root of 721749765 is about 26865.4008903645. The cubic root of 721749765 is about 897.0064179782.

The spelling of 721749765 in words is "seven hundred twenty-one million, seven hundred forty-nine thousand, seven hundred sixty-five".