721287601 has 4 divisors (see below), whose sum is σ = 726552612. Its totient is φ = 716022592.

The previous prime is 721287587. The next prime is 721287643. The reversal of 721287601 is 106782127.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 599074576 + 122213025 = 24476^2 + 11055^2 .

It is a cyclic number.

It is not a de Polignac number, because 721287601 - 2⁵ = 721287569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721287691) 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, 2632300 + ... + 2632573.

It is an arithmetic number, because the mean of its divisors is an integer number (181638153).

Almost surely, 2^721287601 is an apocalyptic number.

It is an amenable number.

721287601 is a deficient number, since it is larger than the sum of its proper divisors (5265011).

721287601 is a wasteful number, since it uses less digits than its factorization.

721287601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5265010.

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

The square root of 721287601 is about 26856.7980407196. The cubic root of 721287601 is about 896.8149145824.

The spelling of 721287601 in words is "seven hundred twenty-one million, two hundred eighty-seven thousand, six hundred one".