721317261 has 16 divisors (see below), whose sum is σ = 1137052800. Its totient is φ = 397967808.

The previous prime is 721317239. The next prime is 721317323. The reversal of 721317261 is 162713127.

It is not a de Polignac number, because 721317261 - 2⁵ = 721317229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721317661) 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 15 ways as a sum of consecutive naturals, for example, 591606 + ... + 592823.

It is an arithmetic number, because the mean of its divisors is an integer number (71065800).

Almost surely, 2^721317261 is an apocalyptic number.

It is an amenable number.

721317261 is a deficient number, since it is larger than the sum of its proper divisors (415735539).

721317261 is a wasteful number, since it uses less digits than its factorization.

721317261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1184468.

The product of its digits is 3528, while the sum is 30.

The square root of 721317261 is about 26857.3502229837. The cubic root of 721317261 is about 896.8272070280.

The spelling of 721317261 in words is "seven hundred twenty-one million, three hundred seventeen thousand, two hundred sixty-one".