663909123720 has 128 divisors (see below), whose sum is σ = 2029715625600. Its totient is φ = 173667047424.

The previous prime is 663909123697. The next prime is 663909123799. The reversal of 663909123720 is 27321909366.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 663909123720.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 51248764 + ... + 51261716.

It is an arithmetic number, because the mean of its divisors is an integer number (15857153325).

Almost surely, 2^663909123720 is an apocalyptic number.

663909123720 is a gapful number since it is divisible by the number (60) 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 663909123720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1014857812800).

663909123720 is an abundant number, since it is smaller than the sum of its proper divisors (1365806501880).

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

663909123720 is a wasteful number, since it uses less digits than its factorization.

663909123720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21079 (or 21075 counting only the distinct ones).

The product of its (nonzero) digits is 734832, while the sum is 48.

The spelling of 663909123720 in words is "six hundred sixty-three billion, nine hundred nine million, one hundred twenty-three thousand, seven hundred twenty".