21166931890800 has 360 divisors, whose sum is σ = 76249940108160. Its totient is φ = 5639013676800.

The previous prime is 21166931890759. The next prime is 21166931890849. The reversal of 21166931890800 is 809813966112.

21166931890800 is a `hidden beast` number, since 2 + 1 + 166 + 9 + 318 + 90 + 80 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (360).

It is a super-3 number, since 3×21166931890800³ (a number of 41 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

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 71 ways as a sum of consecutive naturals, for example, 100107591 + ... + 100318809.

Almost surely, 2^{21166931890800} is an apocalyptic number.

21166931890800 is a gapful number since it is divisible by the number (20) 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 21166931890800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38124970054080).

21166931890800 is an abundant number, since it is smaller than the sum of its proper divisors (55083008217360).

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

21166931890800 is a wasteful number, since it uses less digits than its factorization.

21166931890800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212283 (or 212260 counting only the distinct ones).

The product of its (nonzero) digits is 1119744, while the sum is 54.

The spelling of 21166931890800 in words is "twenty-one trillion, one hundred sixty-six billion, nine hundred thirty-one million, eight hundred ninety thousand, eight hundred".