21039816720 has 320 divisors, whose sum is σ = 73570291200. Its totient is φ = 4935254016.

The previous prime is 21039816703. The next prime is 21039816727. The reversal of 21039816720 is 2761893012.

It is a super-2 number, since 2×21039816720² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21039816727) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 32219914 + ... + 32220566.

It is an arithmetic number, because the mean of its divisors is an integer number (229907160).

Almost surely, 2^21039816720 is an apocalyptic number.

21039816720 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 21039816720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36785145600).

21039816720 is an abundant number, since it is smaller than the sum of its proper divisors (52530474480).

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

21039816720 is a wasteful number, since it uses less digits than its factorization.

21039816720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1154 (or 1148 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 39.

The spelling of 21039816720 in words is "twenty-one billion, thirty-nine million, eight hundred sixteen thousand, seven hundred twenty".