1661489280 has 256 divisors, whose sum is σ = 6420124800. Its totient is φ = 402739200.

The previous prime is 1661489279. The next prime is 1661489303. The reversal of 1661489280 is 829841661.

1661489280 is a `hidden beast` number, since 1 + 6 + 614 + 8 + 9 + 28 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 185710 + ... + 194450.

Almost surely, 2^1661489280 is an apocalyptic number.

1661489280 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 1661489280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3210062400).

1661489280 is an abundant number, since it is smaller than the sum of its proper divisors (4758635520).

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

1661489280 is a wasteful number, since it uses less digits than its factorization.

1661489280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8780 (or 8762 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The square root of 1661489280 is about 40761.3699475373. The cubic root of 1661489280 is about 1184.4021339175.

The spelling of 1661489280 in words is "one billion, six hundred sixty-one million, four hundred eighty-nine thousand, two hundred eighty".