1985661296640 has 1344 divisors, whose sum is σ = 8133903138816. Its totient is φ = 438772432896.

The previous prime is 1985661296629. The next prime is 1985661296651. The reversal of 1985661296640 is 466921665891.

1985661296640 is a `hidden beast` number, since 1 + 9 + 8 + 5 + 6 + 612 + 9 + 6 + 6 + 4 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (1985661296629) and next prime (1985661296651).

It is a tau number, because it is divible by the number of its divisors (1344).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 15635128257 + ... + 15635128383.

It is an arithmetic number, because the mean of its divisors is an integer number (6052011264).

Almost surely, 2^{1985661296640} is an apocalyptic number.

1985661296640 is a gapful number since it is divisible by the number (10) 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 1985661296640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4066951569408).

1985661296640 is an abundant number, since it is smaller than the sum of its proper divisors (6148241842176).

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

1985661296640 is a wasteful number, since it uses less digits than its factorization.

1985661296640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 327 (or 300 counting only the distinct ones).

The product of its (nonzero) digits is 33592320, while the sum is 63.

The spelling of 1985661296640 in words is "one trillion, nine hundred eighty-five billion, six hundred sixty-one million, two hundred ninety-six thousand, six hundred forty".