721973641 has 4 divisors (see below), whose sum is σ = 722476800. Its totient is φ = 721470484.

The previous prime is 721973621. The next prime is 721973671. The reversal of 721973641 is 146379127.

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 721973641 - 2²⁵ = 688419209 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721973594 and 721973603.

It is not an unprimeable number, because it can be changed into a prime (721973621) 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, 249421 + ... + 252298.

It is an arithmetic number, because the mean of its divisors is an integer number (180619200).

Almost surely, 2^721973641 is an apocalyptic number.

It is an amenable number.

721973641 is a deficient number, since it is larger than the sum of its proper divisors (503159).

721973641 is a wasteful number, since it uses less digits than its factorization.

721973641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503158.

The product of its digits is 63504, while the sum is 40.

The square root of 721973641 is about 26869.5671904108. The cubic root of 721973641 is about 897.0991543894.

The spelling of 721973641 in words is "seven hundred twenty-one million, nine hundred seventy-three thousand, six hundred forty-one".