661942043784 has 256 divisors, whose sum is σ = 2259072000000. Its totient is φ = 175359748608.

The previous prime is 661942043753. The next prime is 661942043813. The reversal of 661942043784 is 487340249166.

661942043784 is a `hidden beast` number, since 6 + 61 + 9 + 4 + 204 + 378 + 4 = 666.

It is a super-3 number, since 3×661942043784³ (a number of 36 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 661942043784.

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, 1105092 + ... + 1595340.

It is an arithmetic number, because the mean of its divisors is an integer number (8824500000).

Almost surely, 2^661942043784 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 661942043784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1129536000000).

661942043784 is an abundant number, since it is smaller than the sum of its proper divisors (1597129956216).

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

661942043784 is a wasteful number, since it uses less digits than its factorization.

661942043784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 490337 (or 490327 counting only the distinct ones).

The product of its (nonzero) digits is 6967296, while the sum is 54.

The spelling of 661942043784 in words is "six hundred sixty-one billion, nine hundred forty-two million, forty-three thousand, seven hundred eighty-four".