721756673 has 4 divisors (see below), whose sum is σ = 787370928. Its totient is φ = 656142420.

The previous prime is 721756657. The next prime is 721756687. The reversal of 721756673 is 376657127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 721756673 - 2⁴ = 721756657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721756603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32807111 + ... + 32807132.

It is an arithmetic number, because the mean of its divisors is an integer number (196842732).

Almost surely, 2^721756673 is an apocalyptic number.

It is an amenable number.

721756673 is a deficient number, since it is larger than the sum of its proper divisors (65614255).

721756673 is a wasteful number, since it uses less digits than its factorization.

721756673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65614254.

The product of its digits is 370440, while the sum is 44.

The square root of 721756673 is about 26865.5294569082. The cubic root of 721756673 is about 897.0092797737.

The spelling of 721756673 in words is "seven hundred twenty-one million, seven hundred fifty-six thousand, six hundred seventy-three".