721644340 has 48 divisors (see below), whose sum is σ = 1547300160. Its totient is φ = 282631680.

The previous prime is 721644317. The next prime is 721644367. The reversal of 721644340 is 43446127.

It is a super-3 number, since 3×721644340³ (a number of 28 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 332860 + ... + 335020.

It is an arithmetic number, because the mean of its divisors is an integer number (32235420).

Almost surely, 2^721644340 is an apocalyptic number.

It is an amenable number.

721644340 is an abundant number, since it is smaller than the sum of its proper divisors (825655820).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721644340 is a wasteful number, since it uses less digits than its factorization.

721644340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2512 (or 2510 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 31.

The square root of 721644340 is about 26863.4387225463. The cubic root of 721644340 is about 896.9627410184.

The spelling of 721644340 in words is "seven hundred twenty-one million, six hundred forty-four thousand, three hundred forty".