721313505 has 40 divisors (see below), whose sum is σ = 1410577344. Its totient is φ = 349725600.

The previous prime is 721313501. The next prime is 721313507. The reversal of 721313505 is 505313127.

It is not a de Polignac number, because 721313505 - 2² = 721313501 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (721313501) 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 39 ways as a sum of consecutive naturals, for example, 76501 + ... + 85410.

Almost surely, 2^721313505 is an apocalyptic number.

It is an amenable number.

721313505 is a deficient number, since it is larger than the sum of its proper divisors (689263839).

721313505 is a wasteful number, since it uses less digits than its factorization.

721313505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161939 (or 161930 counting only the distinct ones).

The product of its (nonzero) digits is 3150, while the sum is 27.

The square root of 721313505 is about 26857.2802979006. The cubic root of 721313505 is about 896.8256503904.

The spelling of 721313505 in words is "seven hundred twenty-one million, three hundred thirteen thousand, five hundred five".