721665464 has 96 divisors (see below), whose sum is σ = 1556929920. Its totient is φ = 311496192.

The previous prime is 721665463. The next prime is 721665499. The reversal of 721665464 is 464566127.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721665463) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3236057 + ... + 3236279.

It is an arithmetic number, because the mean of its divisors is an integer number (16218020).

Almost surely, 2^721665464 is an apocalyptic number.

721665464 is a gapful number since it is divisible by the number (74) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721665464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (778464960).

721665464 is an abundant number, since it is smaller than the sum of its proper divisors (835264456).

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

721665464 is a wasteful number, since it uses less digits than its factorization.

721665464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 337 (or 304 counting only the distinct ones).

The product of its digits is 241920, while the sum is 41.

The square root of 721665464 is about 26863.8318934585. The cubic root of 721665464 is about 896.9714929086.

The spelling of 721665464 in words is "seven hundred twenty-one million, six hundred sixty-five thousand, four hundred sixty-four".