1661904540 has 120 divisors (see below), whose sum is σ = 5487950160. Its totient is φ = 419841792.

The previous prime is 1661904529. The next prime is 1661904553. The reversal of 1661904540 is 454091661.

1661904540 is a `hidden beast` number, since 16 + 6 + 190 + 454 + 0 = 666.

It is a super-2 number, since 2×1661904540² = 5523853400145223200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1661904495 and 1661904504.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 3784 + ... + 57776.

It is an arithmetic number, because the mean of its divisors is an integer number (45732918).

Almost surely, 2^1661904540 is an apocalyptic number.

1661904540 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 1661904540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2743975080).

1661904540 is an abundant number, since it is smaller than the sum of its proper divisors (3826045620).

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

1661904540 is a wasteful number, since it uses less digits than its factorization.

1661904540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54033 (or 54022 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 1661904540 is about 40766.4634227695. The cubic root of 1661904540 is about 1184.5007991866.

The spelling of 1661904540 in words is "one billion, six hundred sixty-one million, nine hundred four thousand, five hundred forty".