21124165920 has 384 divisors, whose sum is σ = 78460462080. Its totient is φ = 4709806080.

The previous prime is 21124165913. The next prime is 21124165943. The reversal of 21124165920 is 2956142112.

It is a Harshad number since it is a multiple of its sum of digits (33).

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, 32054551 + ... + 32055209.

It is an arithmetic number, because the mean of its divisors is an integer number (204324120).

Almost surely, 2^21124165920 is an apocalyptic number.

21124165920 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 21124165920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39230231040).

21124165920 is an abundant number, since it is smaller than the sum of its proper divisors (57336296160).

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

21124165920 is a wasteful number, since it uses less digits than its factorization.

21124165920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1168 (or 1160 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The spelling of 21124165920 in words is "twenty-one billion, one hundred twenty-four million, one hundred sixty-five thousand, nine hundred twenty".