721608820 has 12 divisors (see below), whose sum is σ = 1515378564. Its totient is φ = 288643520.

The previous prime is 721608787. The next prime is 721608821. The reversal of 721608820 is 28806127.

It can be written as a sum of positive squares in 2 ways, for example, as 109244304 + 612364516 = 10452^2 + 24746^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721608821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18040201 + ... + 18040240.

It is an arithmetic number, because the mean of its divisors is an integer number (126281547).

Almost surely, 2^721608820 is an apocalyptic number.

It is an amenable number.

721608820 is an abundant number, since it is smaller than the sum of its proper divisors (793769744).

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

721608820 is a wasteful number, since it uses less digits than its factorization.

721608820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36080450 (or 36080448 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 721608820 is about 26862.7775927956. Note that the first 3 decimals coincide. The cubic root of 721608820 is about 896.9480243325.

The spelling of 721608820 in words is "seven hundred twenty-one million, six hundred eight thousand, eight hundred twenty".