21604309440 has 224 divisors, whose sum is σ = 79873205760. Its totient is φ = 4844875776.

The previous prime is 21604309421. The next prime is 21604309453. The reversal of 21604309440 is 4490340612.

It is a tau number, because it is divible by the number of its divisors (224).

It is a super-2 number, since 2×21604309440² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 325831 + ... + 386489.

Almost surely, 2^21604309440 is an apocalyptic number.

21604309440 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 21604309440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39936602880).

21604309440 is an abundant number, since it is smaller than the sum of its proper divisors (58268896320).

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

21604309440 is a wasteful number, since it uses less digits than its factorization.

21604309440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60739 (or 60729 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 33.

It can be divided in two parts, 2160 and 4309440, that multiplied together give a square (9308390400 = 96480²).

The spelling of 21604309440 in words is "twenty-one billion, six hundred four million, three hundred nine thousand, four hundred forty".