720551821 has 8 divisors (see below), whose sum is σ = 786269088. Its totient is φ = 654870000.

The previous prime is 720551761. The next prime is 720551827. The reversal of 720551821 is 128155027.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 720551821 - 2¹⁵ = 720519053 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720551827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51646 + ... + 64096.

It is an arithmetic number, because the mean of its divisors is an integer number (98283636).

Almost surely, 2^720551821 is an apocalyptic number.

It is an amenable number.

720551821 is a deficient number, since it is larger than the sum of its proper divisors (65717267).

720551821 is a wasteful number, since it uses less digits than its factorization.

720551821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17723.

The product of its (nonzero) digits is 5600, while the sum is 31.

The square root of 720551821 is about 26843.0963377923. The cubic root of 720551821 is about 896.5098661402.

The spelling of 720551821 in words is "seven hundred twenty million, five hundred fifty-one thousand, eight hundred twenty-one".