21125721120 has 384 divisors, whose sum is σ = 78926690304. Its totient is φ = 4649508864.

The previous prime is 21125721119. The next prime is 21125721139. The reversal of 21125721120 is 2112752112.

It is a happy number.

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 63 ways as a sum of consecutive naturals, for example, 10546039 + ... + 10548041.

It is an arithmetic number, because the mean of its divisors is an integer number (205538256).

Almost surely, 2^21125721120 is an apocalyptic number.

21125721120 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 21125721120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39463345152).

21125721120 is an abundant number, since it is smaller than the sum of its proper divisors (57800969184).

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

21125721120 is a wasteful number, since it uses less digits than its factorization.

21125721120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2144 (or 2136 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 24.

The spelling of 21125721120 in words is "twenty-one billion, one hundred twenty-five million, seven hundred twenty-one thousand, one hundred twenty".