1661896126800 has 1920 divisors, whose sum is σ = 7794278912000. Its totient is φ = 326517350400.

The previous prime is 1661896126799. The next prime is 1661896126811. The reversal of 1661896126800 is 86216981661.

1661896126800 is a `hidden beast` number, since 1 + 6 + 6 + 18 + 9 + 612 + 6 + 8 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 1139064471 + ... + 1139065929.

Almost surely, 2^{1661896126800} is an apocalyptic number.

1661896126800 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 1661896126800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3897139456000).

1661896126800 is an abundant number, since it is smaller than the sum of its proper divisors (6132382785200).

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

1661896126800 is a wasteful number, since it uses less digits than its factorization.

1661896126800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1586 (or 1569 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 54.

The spelling of 1661896126800 in words is "one trillion, six hundred sixty-one billion, eight hundred ninety-six million, one hundred twenty-six thousand, eight hundred".