720655149521 has 4 divisors (see below), whose sum is σ = 720656863332. Its totient is φ = 720653435712.

The previous prime is 720655149439. The next prime is 720655149527. The reversal of 720655149521 is 125941556027.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 125941556027 = 7 ⋅17991650861.

It can be written as a sum of positive squares in 2 ways, for example, as 507706126225 + 212949023296 = 712535^2 + 461464^2 .

It is a cyclic number.

It is not a de Polignac number, because 720655149521 - 2¹⁸ = 720654887377 is a prime.

It is a super-2 number, since 2×720655149521² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (720655149527) 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, 253325 + ... + 1226981.

It is an arithmetic number, because the mean of its divisors is an integer number (180164215833).

Almost surely, 2^720655149521 is an apocalyptic number.

It is an amenable number.

720655149521 is a deficient number, since it is larger than the sum of its proper divisors (1713811).

720655149521 is an equidigital number, since it uses as much as digits as its factorization.

720655149521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1713810.

The product of its (nonzero) digits is 756000, while the sum is 47.

The spelling of 720655149521 in words is "seven hundred twenty billion, six hundred fifty-five million, one hundred forty-nine thousand, five hundred twenty-one".