721864651 has 2 divisors, whose sum is σ = 721864652. Its totient is φ = 721864650.

The previous prime is 721864643. The next prime is 721864657. The reversal of 721864651 is 156468127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721864651 - 2³ = 721864643 is a prime.

It is not a weakly prime, because it can be changed into another prime (721864657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360932325 + 360932326.

It is an arithmetic number, because the mean of its divisors is an integer number (360932326).

Almost surely, 2^721864651 is an apocalyptic number.

721864651 is a deficient number, since it is larger than the sum of its proper divisors (1).

721864651 is an equidigital number, since it uses as much as digits as its factorization.

721864651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 40.

The square root of 721864651 is about 26867.5389829437. The cubic root of 721864651 is about 897.0540097323.

The spelling of 721864651 in words is "seven hundred twenty-one million, eight hundred sixty-four thousand, six hundred fifty-one".