720817261 has 4 divisors (see below), whose sum is σ = 722444832. Its totient is φ = 719189692.

The previous prime is 720817241. The next prime is 720817277. The reversal of 720817261 is 162718027.

It is a happy number.

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 720817261 - 2¹⁹ = 720292973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720817241) 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, 813121 + ... + 814006.

It is an arithmetic number, because the mean of its divisors is an integer number (180611208).

Almost surely, 2^720817261 is an apocalyptic number.

It is an amenable number.

720817261 is a deficient number, since it is larger than the sum of its proper divisors (1627571).

720817261 is a wasteful number, since it uses less digits than its factorization.

720817261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1627570.

The product of its (nonzero) digits is 9408, while the sum is 34.

The square root of 720817261 is about 26848.0401705599. The cubic root of 720817261 is about 896.6199393538.

The spelling of 720817261 in words is "seven hundred twenty million, eight hundred seventeen thousand, two hundred sixty-one".