21601346640 has 160 divisors (see below), whose sum is σ = 69160573440. Its totient is φ = 5574193152.

The previous prime is 21601346597. The next prime is 21601346671. The reversal of 21601346640 is 4664310612.

It is a super-2 number, since 2×21601346640² (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 (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 993162 + ... + 1014678.

It is an arithmetic number, because the mean of its divisors is an integer number (432253584).

Almost surely, 2^21601346640 is an apocalyptic number.

21601346640 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 21601346640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34580286720).

21601346640 is an abundant number, since it is smaller than the sum of its proper divisors (47559226800).

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

21601346640 is a wasteful number, since it uses less digits than its factorization.

21601346640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21669 (or 21663 counting only the distinct ones).

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

The spelling of 21601346640 in words is "twenty-one billion, six hundred one million, three hundred forty-six thousand, six hundred forty".