21720367536 has 80 divisors (see below), whose sum is σ = 64156012800. Its totient is φ = 6202992384.

The previous prime is 21720367531. The next prime is 21720367547. The reversal of 21720367536 is 63576302712.

It is a super-2 number, since 2×21720367536² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (21720367531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 789175 + ... + 816233.

It is an arithmetic number, because the mean of its divisors is an integer number (801950160).

Almost surely, 2^21720367536 is an apocalyptic number.

It is an amenable number.

21720367536 is an abundant number, since it is smaller than the sum of its proper divisors (42435645264).

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

21720367536 is a wasteful number, since it uses less digits than its factorization.

21720367536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29466 (or 29460 counting only the distinct ones).

The product of its (nonzero) digits is 317520, while the sum is 42.

The spelling of 21720367536 in words is "twenty-one billion, seven hundred twenty million, three hundred sixty-seven thousand, five hundred thirty-six".