721435440 has 80 divisors (see below), whose sum is σ = 2439772416. Its totient is φ = 174892800.

The previous prime is 721435439. The next prime is 721435447. The reversal of 721435440 is 44534127.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 721435398 and 721435407.

It is not an unprimeable number, because it can be changed into a prime (721435447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 133996 + ... + 139275.

Almost surely, 2^721435440 is an apocalyptic number.

It is an amenable number.

721435440 is an abundant number, since it is smaller than the sum of its proper divisors (1718336976).

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

721435440 is a wasteful number, since it uses less digits than its factorization.

721435440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273298 (or 273292 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 30.

The square root of 721435440 is about 26859.5502568453. The cubic root of 721435440 is about 896.8761824053.

Adding to 721435440 its reverse (44534127), we get a palindrome (765969567).

The spelling of 721435440 in words is "seven hundred twenty-one million, four hundred thirty-five thousand, four hundred forty".