2001661611840 has 672 divisors, whose sum is σ = 7693021155456. Its totient is φ = 473616875520.

The previous prime is 2001661611821. The next prime is 2001661611847. The reversal of 2001661611840 is 481161661002.

2001661611840 is a `hidden beast` number, since 20 + 0 + 1 + 6 + 616 + 1 + 18 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 2001661611795 and 2001661611804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001661611847) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 224321619 + ... + 224330541.

It is an arithmetic number, because the mean of its divisors is an integer number (11447948148).

Almost surely, 2^{2001661611840} is an apocalyptic number.

2001661611840 is a gapful number since it is divisible by the number (20) 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 2001661611840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3846510577728).

2001661611840 is an abundant number, since it is smaller than the sum of its proper divisors (5691359543616).

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

2001661611840 is a wasteful number, since it uses less digits than its factorization.

2001661611840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9127 (or 9114 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The spelling of 2001661611840 in words is "two trillion, one billion, six hundred sixty-one million, six hundred eleven thousand, eight hundred forty".