1661500500 has 192 divisors, whose sum is σ = 5335739136. Its totient is φ = 398400000.

The previous prime is 1661500481. The next prime is 1661500507. The reversal of 1661500500 is 50051661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661500507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1666002 + ... + 1666998.

It is an arithmetic number, because the mean of its divisors is an integer number (27790308).

Almost surely, 2^1661500500 is an apocalyptic number.

1661500500 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 1661500500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2667869568).

1661500500 is an abundant number, since it is smaller than the sum of its proper divisors (3674238636).

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

1661500500 is a wasteful number, since it uses less digits than its factorization.

1661500500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1131 (or 1119 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 1661500500 is about 40761.5075776154. The cubic root of 1661500500 is about 1184.4047999919.

It can be divided in two parts, 16 and 61500500, that added together give a palindrome (61500516).

The spelling of 1661500500 in words is "one billion, six hundred sixty-one million, five hundred thousand, five hundred".