21165615200 has 216 divisors, whose sum is σ = 54121020408. Its totient is φ = 8082063360.

The previous prime is 21165615199. The next prime is 21165615209. The reversal of 21165615200 is 251656112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21165615209) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 109666304 + ... + 109666496.

Almost surely, 2^21165615200 is an apocalyptic number.

21165615200 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 21165615200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27060510204).

21165615200 is an abundant number, since it is smaller than the sum of its proper divisors (32955405208).

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

21165615200 is a wasteful number, since it uses less digits than its factorization.

21165615200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434 (or 392 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 29.

The spelling of 21165615200 in words is "twenty-one billion, one hundred sixty-five million, six hundred fifteen thousand, two hundred".