21378709800 has 576 divisors, whose sum is σ = 86506368000. Its totient is φ = 4724697600.

The previous prime is 21378709753. The next prime is 21378709801. The reversal of 21378709800 is 890787312.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21378709801) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 19138842 + ... + 19139958.

Almost surely, 2^21378709800 is an apocalyptic number.

21378709800 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 21378709800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43253184000).

21378709800 is an abundant number, since it is smaller than the sum of its proper divisors (65127658200).

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

21378709800 is a wasteful number, since it uses less digits than its factorization.

21378709800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1191 (or 1165 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 45.

The spelling of 21378709800 in words is "twenty-one billion, three hundred seventy-eight million, seven hundred nine thousand, eight hundred".