661937787936 has 240 divisors, whose sum is σ = 2099187588960. Its totient is φ = 203933998080.

The previous prime is 661937787911. The next prime is 661937787937. The reversal of 661937787936 is 639787739166.

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

It is not an unprimeable number, because it can be changed into a prime (661937787937) 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, 1855255 + ... + 2183081.

It is an arithmetic number, because the mean of its divisors is an integer number (8746614954).

Almost surely, 2^661937787936 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 661937787936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1049593794480).

661937787936 is an abundant number, since it is smaller than the sum of its proper divisors (1437249801024).

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

661937787936 is a wasteful number, since it uses less digits than its factorization.

661937787936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327909 (or 327892 counting only the distinct ones).

The product of its digits is 432081216, while the sum is 72.

The spelling of 661937787936 in words is "six hundred sixty-one billion, nine hundred thirty-seven million, seven hundred eighty-seven thousand, nine hundred thirty-six".