1661001660 has 384 divisors, whose sum is σ = 5878656000. Its totient is φ = 386850816.

The previous prime is 1661001599. The next prime is 1661001739. The reversal of 1661001660 is 661001661.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 15523327 + ... + 15523433.

It is an arithmetic number, because the mean of its divisors is an integer number (15309000).

Almost surely, 2^1661001660 is an apocalyptic number.

1661001660 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 1661001660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2939328000).

1661001660 is an abundant number, since it is smaller than the sum of its proper divisors (4217654340).

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

1661001660 is a wasteful number, since it uses less digits than its factorization.

1661001660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250 (or 242 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 1661001660 is about 40755.3881100401. The cubic root of 1661001660 is about 1184.2862550121.

Subtracting from 1661001660 its reverse (661001661), we obtain a palindrome (999999999).

It can be divided in two parts, 1661001 and 660, that added together give a palindrome (1661661).

The spelling of 1661001660 in words is "one billion, six hundred sixty-one million, one thousand, six hundred sixty".