21135816000 has 840 divisors, whose sum is σ = 85107240504. Its totient is φ = 5175705600.

The previous prime is 21135815969. The next prime is 21135816001. The reversal of 21135816000 is 61853112.

21135816000 is a `hidden beast` number, since 2 + 1 + 1 + 3 + 58 + 1 + 600 + 0 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 21090010176 + 45805824 = 145224^2 + 6768^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135816001) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 109511904 + ... + 109512096.

Almost surely, 2^21135816000 is an apocalyptic number.

21135816000 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 21135816000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42553620252).

21135816000 is an abundant number, since it is smaller than the sum of its proper divisors (63971424504).

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

21135816000 is a wasteful number, since it uses less digits than its factorization.

21135816000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258 (or 216 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The spelling of 21135816000 in words is "twenty-one billion, one hundred thirty-five million, eight hundred sixteen thousand".