21123009600 has 672 divisors, whose sum is σ = 87793714176. Its totient is φ = 4318617600.

The previous prime is 21123009599. The next prime is 21123009671. The reversal of 21123009600 is 690032112.

It is a tau number, because it is divible by the number of its divisors (672).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 24762774 + ... + 24763626.

It is an arithmetic number, because the mean of its divisors is an integer number (130645408).

Almost surely, 2^21123009600 is an apocalyptic number.

21123009600 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 21123009600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43896857088).

21123009600 is an abundant number, since it is smaller than the sum of its proper divisors (66670704576).

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

21123009600 is a wasteful number, since it uses less digits than its factorization.

21123009600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 963 (or 948 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 24.

The spelling of 21123009600 in words is "twenty-one billion, one hundred twenty-three million, nine thousand, six hundred".