21645646000 has 160 divisors (see below), whose sum is σ = 57380184576. Its totient is φ = 7832160000.

The previous prime is 21645645997. The next prime is 21645646003. The reversal of 21645646000 is 64654612.

It is an interprime number because it is at equal distance from previous prime (21645645997) and next prime (21645646003).

It is not an unprimeable number, because it can be changed into a prime (21645646003) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4639669 + ... + 4644331.

Almost surely, 2^21645646000 is an apocalyptic number.

21645646000 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 21645646000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28690092288).

21645646000 is an abundant number, since it is smaller than the sum of its proper divisors (35734538576).

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

21645646000 is a wasteful number, since it uses less digits than its factorization.

21645646000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4908 (or 4892 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 34.

The spelling of 21645646000 in words is "twenty-one billion, six hundred forty-five million, six hundred forty-six thousand".