721821240 has 128 divisors (see below), whose sum is σ = 2749824000. Its totient is φ = 164985984.

The previous prime is 721821227. The next prime is 721821319. The reversal of 721821240 is 42128127.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40180 + ... + 55299.

It is an arithmetic number, because the mean of its divisors is an integer number (21483000).

Almost surely, 2^721821240 is an apocalyptic number.

721821240 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

721821240 is an abundant number, since it is smaller than the sum of its proper divisors (2028002760).

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

721821240 is a wasteful number, since it uses less digits than its factorization.

721821240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95506 (or 95496 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 721821240 is about 26866.7311000054. The cubic root of 721821240 is about 897.0360272327.

Adding to 721821240 its reverse (42128127), we get a palindrome (763949367).

The spelling of 721821240 in words is "seven hundred twenty-one million, eight hundred twenty-one thousand, two hundred forty".