21061814400 has 960 divisors, whose sum is σ = 86774133600. Its totient is φ = 4987699200.

The previous prime is 21061814381. The next prime is 21061814401. The reversal of 21061814400 is 441816012.

It is a happy number.

21061814400 is a `hidden beast` number, since 2 + 1 + 0 + 618 + 1 + 4 + 40 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

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

It is not an unprimeable number, because it can be changed into a prime (21061814401) 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, 236649556 + ... + 236649644.

Almost surely, 2^21061814400 is an apocalyptic number.

21061814400 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 21061814400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43387066800).

21061814400 is an abundant number, since it is smaller than the sum of its proper divisors (65712319200).

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

21061814400 is a wasteful number, since it uses less digits than its factorization.

21061814400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219 (or 193 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The spelling of 21061814400 in words is "twenty-one billion, sixty-one million, eight hundred fourteen thousand, four hundred".