661699772352 has 280 divisors, whose sum is σ = 2069012880000. Its totient is φ = 208523579904.

The previous prime is 661699772309. The next prime is 661699772353. The reversal of 661699772352 is 253277996166.

661699772352 is a `hidden beast` number, since 6 + 616 + 9 + 9 + 7 + 7 + 2 + 3 + 5 + 2 = 666.

It is a super-2 number, since 2×661699772352² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 661699772352.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661699772353) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 49142773 + ... + 49156235.

Almost surely, 2^661699772352 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 661699772352, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1034506440000).

661699772352 is an abundant number, since it is smaller than the sum of its proper divisors (1407313107648).

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

661699772352 is a wasteful number, since it uses less digits than its factorization.

661699772352 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14005 (or 13986 counting only the distinct ones).

The product of its digits is 51438240, while the sum is 63.

The spelling of 661699772352 in words is "six hundred sixty-one billion, six hundred ninety-nine million, seven hundred seventy-two thousand, three hundred fifty-two".