661698588672 has 832 divisors, whose sum is σ = 2228413317120. Its totient is φ = 192297369600.

The previous prime is 661698588659. The next prime is 661698588731. The reversal of 661698588672 is 276885896166.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a self number, because there is not a number n which added to its sum of digits gives 661698588672.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4059500463 + ... + 4059500625.

Almost surely, 2^661698588672 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661698588672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1114206658560).

661698588672 is an abundant number, since it is smaller than the sum of its proper divisors (1566714728448).

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

661698588672 is a wasteful number, since it uses less digits than its factorization.

661698588672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325 (or 297 counting only the distinct ones).

The product of its digits is 418037760, while the sum is 72.

The spelling of 661698588672 in words is "six hundred sixty-one billion, six hundred ninety-eight million, five hundred eighty-eight thousand, six hundred seventy-two".