1661597700 has 144 divisors (see below), whose sum is σ = 5598391680. Its totient is φ = 372602880.

The previous prime is 1661597699. The next prime is 1661597719. The reversal of 1661597700 is 77951661.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 103836 + ... + 118764.

It is an arithmetic number, because the mean of its divisors is an integer number (38877720).

Almost surely, 2^1661597700 is an apocalyptic number.

1661597700 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 1661597700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2799195840).

1661597700 is an abundant number, since it is smaller than the sum of its proper divisors (3936793980).

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

1661597700 is a wasteful number, since it uses less digits than its factorization.

1661597700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15006 (or 14999 counting only the distinct ones).

The product of its (nonzero) digits is 79380, while the sum is 42.

The square root of 1661597700 is about 40762.6998615156. The cubic root of 1661597700 is about 1184.4278959628.

The spelling of 1661597700 in words is "one billion, six hundred sixty-one million, five hundred ninety-seven thousand, seven hundred".