21018692135808 has 448 divisors, whose sum is σ = 64297811318400. Its totient is φ = 6837253161984.

The previous prime is 21018692135803. The next prime is 21018692135821. The reversal of 21018692135808 is 80853129681012.

21018692135808 is a `hidden beast` number, since 21 + 0 + 18 + 6 + 9 + 21 + 3 + 580 + 8 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21018692135803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 7940569941 + ... + 7940572587.

Almost surely, 2^{21018692135808} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21018692135808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32148905659200).

21018692135808 is an abundant number, since it is smaller than the sum of its proper divisors (43279119182592).

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

21018692135808 is an equidigital number, since it uses as much as digits as its factorization.

21018692135808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4701 (or 4674 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 54.

The spelling of 21018692135808 in words is "twenty-one trillion, eighteen billion, six hundred ninety-two million, one hundred thirty-five thousand, eight hundred eight".