1861821995544 has 288 divisors, whose sum is σ = 5936482375200. Its totient is φ = 525551846400.

The previous prime is 1861821995533. The next prime is 1861821995557. The reversal of 1861821995544 is 4455991281681.

1861821995544 is a `hidden beast` number, since 1 + 8 + 6 + 1 + 82 + 1 + 9 + 9 + 5 + 544 = 666.

It is a super-2 number, since 2×1861821995544² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 173526372 + ... + 173537100.

It is an arithmetic number, because the mean of its divisors is an integer number (20612786025).

Almost surely, 2^{1861821995544} is an apocalyptic number.

1861821995544 is a gapful number since it is divisible by the number (14) 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 1861821995544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2968241187600).

1861821995544 is an abundant number, since it is smaller than the sum of its proper divisors (4074660379656).

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

1861821995544 is a wasteful number, since it uses less digits than its factorization.

1861821995544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11343 (or 11329 counting only the distinct ones).

The product of its digits is 24883200, while the sum is 63.

The spelling of 1861821995544 in words is "one trillion, eight hundred sixty-one billion, eight hundred twenty-one million, nine hundred ninety-five thousand, five hundred forty-four".