721660100 has 72 divisors (see below), whose sum is σ = 1811425728. Its totient is φ = 244425600.

The previous prime is 721660091. The next prime is 721660133. The reversal of 721660100 is 1066127.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51890 + ... + 64310.

Almost surely, 2^721660100 is an apocalyptic number.

721660100 is a gapful number since it is divisible by the number (70) 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 721660100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (905712864).

721660100 is an abundant number, since it is smaller than the sum of its proper divisors (1089765628).

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

721660100 is a wasteful number, since it uses less digits than its factorization.

721660100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12525 (or 12518 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 721660100 is about 26863.7320564362. The cubic root of 721660100 is about 896.9692705645.

The spelling of 721660100 in words is "seven hundred twenty-one million, six hundred sixty thousand, one hundred".