721675651 has 4 divisors (see below), whose sum is σ = 759658600. Its totient is φ = 683692704.

The previous prime is 721675631. The next prime is 721675657. The reversal of 721675651 is 156576127.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 156576127 = 317 ⋅493931.

It is a cyclic number.

It is not a de Polignac number, because 721675651 - 2⁹ = 721675139 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721675657) 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, 18991446 + ... + 18991483.

It is an arithmetic number, because the mean of its divisors is an integer number (189914650).

Almost surely, 2^721675651 is an apocalyptic number.

721675651 is a deficient number, since it is larger than the sum of its proper divisors (37982949).

721675651 is a wasteful number, since it uses less digits than its factorization.

721675651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37982948.

The product of its digits is 88200, while the sum is 40.

The square root of 721675651 is about 26864.0214971623. The cubic root of 721675651 is about 896.9757134263.

The spelling of 721675651 in words is "seven hundred twenty-one million, six hundred seventy-five thousand, six hundred fifty-one".