1661536500 has 192 divisors, whose sum is σ = 5256625920. Its totient is φ = 405388800.

The previous prime is 1661536493. The next prime is 1661536507. The reversal of 1661536500 is 56351661.

It is an interprime number because it is at equal distance from previous prime (1661536493) and next prime (1661536507).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661536507) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2710194 + ... + 2710806.

It is an arithmetic number, because the mean of its divisors is an integer number (27378260).

Almost surely, 2^1661536500 is an apocalyptic number.

1661536500 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 1661536500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2628312960).

1661536500 is an abundant number, since it is smaller than the sum of its proper divisors (3595089420).

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

1661536500 is a wasteful number, since it uses less digits than its factorization.

1661536500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 787 (or 775 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 33.

The square root of 1661536500 is about 40761.9491683114. The cubic root of 1661536500 is about 1184.4133541602.

The spelling of 1661536500 in words is "one billion, six hundred sixty-one million, five hundred thirty-six thousand, five hundred".