21644061420 has 24 divisors (see below), whose sum is σ = 60603372144. Its totient is φ = 5771749696.

The previous prime is 21644061409. The next prime is 21644061437. The reversal of 21644061420 is 2416044612.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 180367119 + ... + 180367238.

It is an arithmetic number, because the mean of its divisors is an integer number (2525140506).

Almost surely, 2^21644061420 is an apocalyptic number.

21644061420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21644061420 is an abundant number, since it is smaller than the sum of its proper divisors (38959310724).

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

21644061420 is a wasteful number, since it uses less digits than its factorization.

21644061420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360734369 (or 360734367 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The spelling of 21644061420 in words is "twenty-one billion, six hundred forty-four million, sixty-one thousand, four hundred twenty".