21009780000 has 840 divisors, whose sum is σ = 85185744336. Its totient is φ = 5054400000.

The previous prime is 21009779983. The next prime is 21009780007. The reversal of 21009780000 is 8790012.

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 (21009780007) by changing a digit.

It is a polite number, since it can be written in 139 ways as a sum of consecutive naturals, for example, 160379935 + ... + 160380065.

Almost surely, 2^21009780000 is an apocalyptic number.

21009780000 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 21009780000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42592872168).

21009780000 is an abundant number, since it is smaller than the sum of its proper divisors (64175964336).

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

21009780000 is an equidigital number, since it uses as much as digits as its factorization.

21009780000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190 (or 152 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The spelling of 21009780000 in words is "twenty-one billion, nine million, seven hundred eighty thousand".